[Closed] +25bhp Performance Chip

There was a massive thread a while back featuring some bad Teds arguing about engine re-mapping. I do not recommend a search.
I believe the arguments against a beefy re-map are that you've stuck some serious power into the engine but you might still be driving round on the shocks, brakes, tyres and transmission of your typical family hatchback. So it's only part of the story in modding the motor.

Of course the chip you're talking about seems relatively restrained so that shouldn't be a big problem. Impressed it works tbh - I'd assume a £20 chip would be bollox.

I suspect your calculations are optimistic, but I have 2 vag tdi's with ecu remap and they have substantialy increased power and power delivery. Not seen a massive improvement in mpg but the seat Ibiza has done 900 miles on £108 of diesel on a combination of motorway, urban and raggin it.

That site says it just connects to the inlet temp sensor. so probably just adjusts that one reading to affect fueling. That is some seriously sucky way to tune an engine.

Skip it IMO.

Just NO

That site says it just connects to the inlet temp sensor.

Ugghh the old power resistor of justice.

It doesn't differentiate between petrol and diesel.

You're running around with the choke on, that seems to be all.

How can running around with the choke on improve economy? However I'd still invest in a proper ecu map not a bolt on. We had one a mitso warrior and it was shit!!

Oh and if you crash open the bonnet and "pull it off" otherwise insurance fail!

I'm dubious of these remaps, you can't get more for nothing / or less. Sure you can alter where the power is delivered or tweak parameters to get a [i]slight[/i] increase in power or an improvement in fuel efficiency but the claims are usually closer to 20% improvements.

Considering car manufacture sell cars of performance and economy it seems strange that they would leave that much room for improvement via a simple task of re-flashing a chip with some slightly different code. It seems like the magnet scam to me . Dose anyone here really know about them? Some independent laboratory tests rather then my "mate stories"?

What i want is science not a big, "oh no dont do that, i paid £300 for a propper remap and wish id spent £20" every forum has that on it.

Its a resistor thats all, but it increases economy wildly so how is that bad.

Science please, not oh no dont do it!!

75mpg?

I seriously doubt that. Where's your working out? If that's just a quick look at the trip computer on the motorway then I can get 65mpg out of our petrol Focus, so I don't believe a word of it.

Come back when you've got accurate records based on at least 5 full tanks of fuel worked out from the trip meter and the amount of fuel that went in, then we can talk.....

The science bit is easy. Go and read how engine management works, then consider the effect of simply altering a reading from one (of the many) sensor(s). You will to come to the same conclusion.

There was a thread on the FIAT Punto forum a while back. It basically concluded that you're best off leaving it to the Nova/Corsa driving chavs. Loads of science there too, CBA to find it though (googling FIAT Punto chipping should be good enough).

I'm not sure how simply chucking more fuel in can help? That is after all what the resistor is doing. A decent remap however should offer some gains from factory set up. But if you want to save fuel drive slower

I'vemate, no, seriously I'veamate that tunes SMART cars.
He bought this ECU remap setup from a tuning company in Germany who'd been developing the early 599cc engined ones. Evil Twin they're called. Anywhoo's I've driven both a mapped and non mapped 700cc cars he's had and there is a massive differance in stage 1 remaps to standard. Ok it's never going to set the lights alight but the remapped version was quicker, easier to accellerate, smoother gear changes (auto remapped at the same time, a big problem with auto SMARTS) and.. yup you guessed it more MPG, ok not a fat lot more he said but C15% more. So combined with the better driving experiance the £200.00 it cost was way worth it (in his opinion) Oh yeah.. these maps are supported by MercUK too.

But it's your dollars, like anything you have to way up whether it's a viable purchase..
Ya pays ya money..yadda yadda

[b]TheBrick[/b] - I'm dubious of these remaps, you can't get more for nothing / or less. Sure you can alter where the power is delivered or tweak parameters to get a slight increase in power or an improvement in fuel efficiency but the claims are usually closer to 20% improvements.

Considering car manufacture sell cars of performance and economy it seems strange that they would leave that much room for improvement via a simple task of re-flashing a chip with some slightly different code. It seems like the magnet scam to me . Dose anyone here really know about them? Some independent laboratory tests rather then my "mate stories"?

Modern remaps do work, although the figures promised can be a tad optimistic. I have a Superchips remap on my 2.0TDI Seat Leon (140bhp) and the change in driving characteristics of the engine are quite significantly. If you boot it all the time economy will suffer but in 'normal' driving I get no less than before I had it done..

There are lots of reasons why manufacturers de-tune their engines - insurance groups, reliability, emissions targets, varying fuel quality in different countries. For example, the BMW 320d and 318d are in essence the same engine but with different maps and slightly differing ancilliaries.

The chip described here though, just fools the engine into thinking it needs more fuel/air mixture and just chucks it in when you boot it.. not the best way of doing it!

@bland, science usually involves running tests on subjects, we ran a test as said above on a mitso warrior, the one we bought was shit and at the time a waste of £200, that scientific enough.
@ the brick, remaps do work when done properly on the ecu, however to achieve the extra 45 bhp on mine it also had the prodrive exhaust fitted. I can most certainly vouch for the fact it improves performance massively (especially around the mid range) as I owned the same car, one with performance pack on and one without. However it does not improve economy in this scenario, possibly the opposite due to "having it under your right foot"!

+25bhp?

Really?

Measured on an engine dyno by an independent company?

Or measured on a chassis dyno to give wheel hp and engine hp 'calculated' (i.e. guessed at)?

This chip doesn't put more fuel in - it just leans the mixture out by reducing the ohm's read from the sensor via a resistor.

This may well make the mpg go up, but at the expense of any longevity of the engine and will in no way increase power (most likely decrease if put on a RR which they are banking at £25 nobody will).

It also won't differentiate from different ambient temperatures, so you fuel and power will more prone to fluctuate on a warm or cold day.

Seriously, spending £10 on a book about engine management would be a much better investment than this product. It would save people £15 immediately and a lot more in the long run.

If I was going to remap my old TDi, it would be with the aim of more low range torque, not speed.

Bland, my car puts out a real +50hp to a measured 240hp. That took a lot of careful ECU work, and then it was set up properly on the dyno to get the best results. I have the before/after graphs, together with the in-progress ones showing the effects of the final tweaks to iron out flat spots and increase responsiveness.

The guy who had it done paid £850 for the 2-day job (the receipt came with the car's papers) and it's definitely quicker/smoother than the original. It's even 10% more economical, though this just means it hits 30mpg rather than 27. What it doesn't feel like is a tuned engine, just an improved version of the original. There's no clouds of soot on acceleration (often the case with tuning boxes, they just chuck in more fuel), and there are no problems with the EGR (again, this can suffer with cheap tuning boxes). You may also have an issue with your injectors over time (you can damage them if there are boost spikes).

My car's now done 130k miles, 40k of which were with the engine work. If you can get these sorts of results (or better) for £20 then good luck to you.

it just leans the mixture out by reducing the ohm's read from the sensor via a resistor

Leans the mixture? It's a diesel.

The cheap chips do not do your engine any good at all. Your ECU is a complex system of sensors and feedback, and what you're doing is hacking it in the worst possible way.

You CAN get more power and possibly more economy out of an engine, but with a proper re-map, where someone's taken time to analyse the behaviour of the engine and tweak the manufacturer's settings to get improvements without messing anything else up. Using the mechanisms that the car was designed to use.

im amazed as its meant to put more fuel in

It puts more fuel in when you ask for it. When you drive, you don't control the speed of your car directly, you control how much fuel is being put in. More fuel = more power = more speed. So driving at 60mph requires a set amount of fuel, regardless of how your ECU is mapped. When you talk about more power here you mean a higher MAXIMUM power, which means that only when you mash the pedal more fuel is being put in than before.

Re fuel economy - this is a complex issue. Diesel efficiency is affected by the injection timing, amongst other things. More advanced injection means more power and more efficiency (up to a point of course) but also more noise and more NOx pollution emissions. When the car's cold, it'll advance injection timing too, so this might be what you're experiencing. The exhaust will run hotter if you drive like this all the time, so it might lunch your turbo, you never know 🙂 It also might stop EGR which is another pollution reduction strategy.

Diesel remaps always claim to increase fuel economy, but it's hotly debated. The best bet seems to be either injection timing as above or more low-down torque, which would allow you to use higher gears more often. Not really an issue on motorway cruises tho.

^^^^ science ^^^^ there

you've stuck some serious power into the engine but you might still be driving round on the shocks, brakes, tyres and transmission of your typical family hatchback.

I had my Golf V6 remapped (custom remap with rolling road tests before and after) and got about 10% more bhp but the main difference was it just revved better (hard to quantify in a sentence, but is so much nice to drive).

Anyway, big downside is insurance - I declared it and my premium doubled and most insurers will no longer touch a modified car - so it gets harder and harder each year to find anyone who will quote (other than specialists who charge a small fortune).

Remap cost £300 ish 7 years back - cumulative hike in premiums must be about £4k by now!

Why on earth would you want to make a family car faster? Surely the extra insurance premiums would cancel out any gains in economy, and presumably the car is already capable of travelling at the speed limit.

Now a chip to make the rear bigger so I could get more bikes in, that would be interesting 🙂

I think the chip just makes your mileometer run faster so you think you're getting better mpg.

Weird, but I have this little button on the console of our XF that says "dynamic mode" on it.

When I push it ... I assumed it altered the mapping of the engine (either that or the bloke under the bonnet started peddling a damn site faster) as it sure goes a fair whack quicker.

Kind of figured if the manufactures are doing this sort of thing, the aftermarket brigade would be over it as well.

Did have a tuning box fitted briefly to a previous X3 2.0d (ended up trading it a month after fitting) Plugged into the wiring harness and had an adjustable level of stupidness from economy to detonation.

Had it set at the lower / mid range and got a few more MPG (according to the clock), and a significant increase in performance (mainly mid range (overtaking / motorway entry) where it normally lacked). Made a fairly tiresome vehicle much more drivable.

Remaps can work very well as they're designed for maximum real world performance and economy, not headline 0-60 times and those silly artificial economy tests which determine CO2 output and thus your car tax. VAG are particularly notable for compromising real economy for lower claimed CO2 figures.

The 'dynamic' mode button will more than likely just change the pedal map rather than actually increasing power. A normal pedal map will allow for a smooth increase in fuelling as the pedal is depressed - the sport (or dynamic or whatever) mode will make the pedal travel to fuelling ratio much sharper at the bottom end so that you get more fuelling when you start to depress the throttle pedal.

So in a way it does increase the power at that specific pedal position, but 100% throttle will still be the same fuelling regardless of the mode. If that makes sense?....

VAG are particularly notable for compromising real economy for lower claimed CO2 figures

How does that work then?

(and remember the govt tests are not claims of fuel economy)

As has been said before, those boxes contain a reisitor and not much else. Cost about 20p i believe. Tricks the ECU into putting more fuel into the engine, which as far as desiel is concerned means more power. They work, but its mixed bag as you dont realy know how the ecu is mapped thoughout the rev range, it wont smooth out the peaks and troughs within the power delivery.

As for why manufactures dont do this from the off, its down to money. The manufactures just want to able to take turbo from batch a and stick it onto engine from batch b and get power x from it. The software is generic to make stated figures. By way of example, last time i mapped my own car, i used a custom from a car with identical set up. Power was down by around 5%, although torque was up. To acheive teh same power i had tweak the fueliing/ignition slightly. Manufactures aren't going to twaek each car induvidually to achieve the best results.

I think it's also down to reliability. Engines are over-built, because they don't want 10% of them going pop at 150k miles or whatever. However if you decide to mess with it and it goes pop, you've taken responsibility yourself.

The science bit is...

Fuel air mix of a diesel is metered out by the ECU after it has measured air temp, RPM and air pressure in the manifold, from these measurements it determines how much air is going into the cylinders. It selects the correct amount of fuel to add for that amount of air. By confusing the resistor for air temp your ECU calculates the wrong amount of air and so meters inthe wrong amount of fuel. In a diesel, without a throttle, the power of the engine is limited by the amount of fuel and air going into the cyl, more or less, and so if your standard mapping is a bit lean in a few spots (to present maybe a better emissions profile or lower smoke output, or protect the clutch/fly from excessive torque) and your resistor richens those bits up which gives you more oomph at the expense of the earlier points.

The resistor also affects teh point at which the fuel is injected on a modern car, which also affects torque and emissions, and may also affect the allowable boost level.

So what you're doing is baffling the ECU into producing a dirty excess of fuel. It could be incorrectly timed, damaging and polluting, but it will work. Doesn't make it ideal of course.

Most manufacturers don't have time to individually map each engine, or create an engine block/setup for each power level, so they just make one and push it harder on the faster versions.

A common one on one of the cars I drive is it has a flapper style air flow meter, people would adjust the spring tension to lean out the mixture, but then forget that that advances the timing too and end up smashing pistons to bits with knock.

Anyway, big downside is insurance - I declared it and my premium doubled and most insurers will no longer touch a modified car - so it gets harder and harder each year to find anyone who will quote (other than specialists who charge a small fortune).

My insurance premium going from a bone-stock car to a highly modified, 50% extra power, different engine, standalone engine management, gearbox, turbo, intercooling, brakes, shocks, wheels.... version was approximately £100 (petrol, turbocharged), 150 with a guaranteed valuation. You're not looking hard enough 🙂 Of course the direct lines of the world won't insure you, but there are a good number of cheap modded car companies who will, and cheaply.

it just leans the mixture out by reducing the ohm's read from the sensor via a resistor

Leans the mixture? It's a diesel

His car maybe (missed that - why would anyone want to "tune" a derv?!). However the product itself is not specifically designed for diesels.

Will any of these chip/flash updates provide ONLY economy improvement for people who say they don't want or need all that power anyway? They all sell themselves on "more power" as if that's what everyone wants. I don't want it, my tdci Ford has plenty to get me prosecuted, - I'd be happy with 30-50% power reduction if I could get better MPG.

missed that - why would anyone want to "tune" a derv?!

Same reason as any other car. The people I rang about it said my 140 would go to 190bhp, and still do 50+mpg. Hard to argue with figures like that 🙂

Will any of these chip/flash updates provide ONLY economy improvement for people who say they don't want or need all that power anyway?

And that's the reason I was on the phone to them in the first place. VW Bluemotion diesels are apparently mapped differently to improve economy, I wanted to know if there was anything they could do to improve my economy other than the fairly vague and unsubstantiated claims on their website. They were only interested in more power really.

From working on similar projects, the Bluemotion will be calibrated to within an inch of it's life for fuel economy during the NEDC cycle (the official cycle EU cars are tested on). Although there might be some gains available for real world economy, again they would be pretty small before you start getting into power loss or severe driveability/noise issues. Pretty much all of the current 'eco' versions of diesels out there are at the limit of fuel consumption for what you can get out of the technology they use. To get further increases you will have to wait until the next gen engine models start to be used.

Hard to argue with figures like that

a) If they are true. Which I doubt. You won't have 140bhp to start with, no matter what they claim.....

b) Until the extra power wrecks your expensive clutch

c) And you start getting through tyres faster

d) etc, etc.

If you want a faster more powerful car, buy one. 🙂

From working on similar projects

I'm interested in the technical aspects if you care to share?

Presumably the 'next gen' is what, solenoid valves? Variable compression/expansion ratios?

You won't have 140bhp to start with, no matter what they claim

I assume you are familiar with the term 'nominal figure'?

Anyway I called them about fuel economy, not interested in extra power for the above reasons.

The reason all these chips work is Manufactures have to produce vehicles that pass the European new vehicle (homologation) emission standards (currently EURO 5). These are a million times more draconian than the MOT test. Also manufacturers are taxed on the amount of CO2 their vehicles produce so they are 'tuned' to produce minimum CO2 and pass the EURO 5 emission regs.

Neither of the above give you the best power, torque or MPG. All these tuning companies are doing is recalibrating the mapping for power and/or mpg which are restricted by conforming to the EURO 5 new vehicle standards, they may also disable emissions equipment such as EGR.

I work for a manufacturer.

How is minimum CO2 not proportional to MPG? NOx I understand, but not CO2.

missed that - why would anyone want to "tune" a derv?!

Same reason as any other car. The people I rang about it said my 140 would go to 190bhp, and still do 50+mpg. Hard to argue with figures like that

It's just figures though. The 190bhp (if they got it) will be peaky as hell. Reached clattering at 4000rpm and gone by 4002!

It's your car and cash at the end of the day. But having your cake (200bhp) and eating it (50mpg) rarely happens without massive compromises.

Look I'm not saying it's a good thing - the question was, why tune a diesel? So I answered it.

But having your cake (200bhp) and eating it (50mpg) rarely happens without massive compromises

I quite fancy the 170bhp Passat TDi...

It's just figures though. The 190bhp (if they got it) will be peaky as hell. Reached clattering at 4000rpm and gone by 4002!

It's generally not that bad though.

So noisy and heavy are your specific compromises then! Have you heard the new Passat when deploying those ponies? It would make your ears bleed in tunnels. My aircooled camper sounds refined next to it 😀

It's just figures though. The 190bhp (if they got it) will be peaky as hell. Reached clattering at 4000rpm and gone by 4002!

It's generally not that bad though.

O.K I admit, I'm a derv hater. Possibly because none of my 3 motors does better than 28mpg. But then I didn't buy them for economy..

if its a diesel specific chip, it does work.

mass produced Diesels are designed and tuned to run on supermarket watered down fuel in countries where its pish

if you get the "bolt on" chip, it tunes it back up as if its being run on quality stuff (shell).
running super market fuel in it, it will be better on all counts, but knacker it quicker too as its trying to burn more efficiently than the fuel will allow.
running it on nicer fuel only, and you will get better speed, torque and mpg, with little in the way of penaltys.

these chips (boxes of toys, not simple resistors) plug onto the ecu connector, not under the bonnet, and mess with the computers calculations (admittedly in a pretty blunt, and generalised way)

...as far as i understand it anyway!

if you get the "bolt on" chip, it tunes it back up as if its being run on quality stuff (shell)

Not really sure I agree with that. If you are talking about injection timing, then it should adjust the timing as it goes along anyway I reckon.

Molgrips, CO2 is inversely proportional to MPG. But a car optimised very precisely for the best performance in a complex lab test will not give you the best MPG or lowest CO2 output in the real world.

Gotcha.

Chiefgrooveguru, you speak the truth.

gwj72, have you actually got any eperience of a good modern diesel engine? Something like the Jaguar/Landrover/Peugeot/Citroen 3.0 ltr V6. In standard form gives 280 bhp & 400lbs/ft of torque and from the outside you'll have trouble telling it from a petrol at idle.

His car maybe (missed that - why would anyone want to "tune" a derv?!).

Jeez, these threads.

Ignoring for a minute the "you'll break it arguements (because you won't), the economuy gains (you won't see) and the modest power gains (which can be had).

What's the point? The last time I drove in the UK all the much, much, more powerful vehicles than the one I was driving seemed to achieve was a zap of gratuitous acceleration before braking as the gap to the vehicle in fornt diminished. A sort of "I'm a frustrated prisoner of this metal box and this trafic saturated road" statement.

I actually agree with you 100% there Edukator. Fast cars on British roads are a mug's game. The best fun you can have is swoopy open country roads, and any reasonably decent handling car will do you just fine 🙂

Pretty much all of the current 'eco' versions of diesels out there are at the limit of fuel consumption for what you can get out of the technology they use. To get further increases you will have to wait until the next gen engine models start to be used.

Ye but savings can be made elsewhere. Underbody aero panels, aero wheels, start/stop engine, high gearing, turbo ... kinetic energy recovery... some of these would obviously push the price of the car up significantly

One of the vehicles I most enjoyed driving didn't even have good handling, thankfully it lhad lots of steering lock to compensate (my Welsh Water Marina van). Having a set of forestry commission keys to go with it was more important.

Ye but savings can be made elsewhere. Underbody aero panels, aero wheels, start/stop engine, high gearing, turbo ... kinetic energy recovery.

Apart from the turbo, Toyota are already there 🙂

Just get a TVR .. no remap needed... family friendly.. not many things to go wrong..

they even emit a safety warning to other motorists as you are heading toward them

Apart from the turbo, Toyota are already there

what model?

The Volvo C30 has all that.. except the kinetic energy recovery

Prius. Recovers kinetic energy to the batterry. The most aerodynamic production car in the world. Transmission has the effect of a CVT but with an enormous gear range, and it also shuts off when going down hills or just lifting off slightly. Asymmetric piston stroke giving greater expansion than compression. Coolant circuit in the exhaust to warm it up super quickly. Electric power for slow speed traffic and manoevring. Fuel tank bladder to stop harmful hydrocarbons escaping when you fill up.. and so on.

Ye but savings can be made elsewhere. Underbody aero panels, aero wheels, start/stop engine, high gearing, turbo ... kinetic energy recovery... some of these would obviously push the price of the car up significantly

Sorry, yes absolutely, I was talking more of benefits purely from engine calibration. Aero and weight are the biggest ones. Unfortunately these are the easiest ones to 'fiddle' for the official emissions test and so gain quite a large chunk of CO2/fuel consumption. Not that any vehicles specifically mentioned on this thread fall foul of that of course.......

I'm interested in the technical aspects if you care to share?

Can't share a huge amount unfortunately as, although our involvement in the project is public knowledge, the calibration strategy itself is definitely not!

I've worked on both the latest Volvo DRIVe vehicles and also the Zafira Ecoflex. Both involved a huge amount of re-calibration of the engine in order to meet client CO2 targets whilst staying within EU emissions limits. I have to say, as a company we also endeavour to greatly improve real-world fuel consumption performance as well and indeed we did a lot of work with the Volvo's in that respect. Ditto with driveability and noise - they shouldn't be any different to drive than the other diesels in the range.

Presumably the 'next gen' is what, solenoid valves? Variable compression/expansion ratios?

Not really that 'high-tech', more just that the current engines being used in eco-models are three or four years old and probably based on blocks older than that. Main benefits in the next few years will come from higher pressure fuel systems and piezo injectors, better combustion chamber design, variable geometry turbos and the use of other aftertreatment such as SCR (which will cut the amount of EGR required). Most of the technology is there, it's just waiting for manufacturers to design engines with it in!

Prius. Recovers kinetic energy to the batterry. The most aerodynamic production car in the world. Transmission has the effect of a CVT but with an enormous gear range, and it also shuts off when going down hills or just lifting off slightly. Asymmetric piston stroke giving greater expansion than compression. Coolant circuit in the exhaust to warm it up super quickly. Electric power for slow speed traffic and manoevring. Fuel tank bladder to stop harmful hydrocarbons escaping when you fill up.. and so on

Yeah it is impressive... the one problem with it though is the battery... expensive to manufacture in environmental terms IIRC

I've worked on both the latest Volvo DRIVe vehicles

May I congratulate you on a job well done then, because if the stats are close to the real world they are excellent.

Are certain manufacturers further from the stats than others then?

My ideas for more efficient engines include small displacement V6s where you can switch off one bank (like big American trucks) thereby reducing the amount of air you're needlessly compressing; and a two stroke two cylinder design with high pressure air supplied by an external compressor and accumulator.

expensive to manufacture in environmental terms IIRC

Yeah that's what the haterz say but there's no real evidence that I've been able to find. Lots of recycled nickel goes into batteries for example. Plus the factory Toyota make the cars in is pretty eco friendly too, something that gets overlooked.

Audi seem to be having moderate success at Le Mans with a diesel.

Go on then, name another diesel race car. 🙂

I can think of one, off the top of my head.....

Le Mans is a pretty special case though!

Your two-stroke sounds like a ship engine, Molgrips.

Go on then, name another diesel race car.

I can think of one, off the top of my head.....

Peugeot 908 (also in LeMans)
Ricardo-Judd engined LMP from a few years ago
Seat Leon (one of the most successful touring cars of modern times)
JCB Dieselmax (not a race car, but has the land speed record for a wheel driven vehicle)

I think there are a few more but those are the main ones!

May I congratulate you on a job well done then, because if the stats are close to the real world they are excellent.

Are certain manufacturers further from the stats than others then?

I'm not going to lie and say they are exactly the same as you have to make compromises to hit the CO2 target in the NEDC test zone - but they are as close as you are probably going to get. Volvo made a big deal about getting real world fuel economy good as in the home market they would get shredded if people replaced their current Volvos and didnt get at least the same or better fuel economy.

The NEDC test is defined around a set of coastdown terms which are notoriously simple to fudge. Some manufacturers fudge them a lot more than others. Unfortunately that is one area we don't have control over when we calibrate an engine and so have to go with what we are given. The Volvo ones were certainly realistic though - they are easily the most honest company I have worked with.

Your two-stroke sounds like a ship engine, Molgrips

Hmm, interesting, not familiar with those. I forsee that the issue with this design would be a suitable compressor.

One day I'll buy old cars and bodge these crazy ideas into them, see how I get on 🙂

Some manufacturers fudge them a lot more than others.

I don't suppose you can tell us which ones? Anecdotally, BMW are bad for this - but that could be because BMW drivers like to boot their cars about - and also Fiat are getting slammed for the real world economy of their Twin Air 500.

I don't suppose you can tell us which ones?

I could, but then I'd have to kill you......

In all serious, it's probably best not to just in case.... Some we have 'evidence' for and others you can just tell that something is a bit dodgy when you look at all the numbers. I'm sure a slightly less unscrupulous engineer has put them somewhere up on the big wide web!

Well I should let you all know that I can get the govt figures from both the Prius and the Passat in summertime, whilst sticking to the speed limit 🙂

Diesels.......Take as mentioned as a good modern example - the jag 3.0 diesel. Only 271bhp from 3 litres with 2 turbo's. Peak power at 4k. That's good? My 1996 petrol car mullers it for power with lower displacement, half as many blowers and another 3k before I hit my redline.

That's not progress chaps. It does 48mpg while I average 24. Definitely an advantage on that front I guess.

Some good points and discussion there chaps.

In summary my plan is to run this 20p resistor for the next tank of fuel, (i put in 50 litres at 136.9 totalling £68.45) thats just so i remember when i tap the figures into fuel economy calculator.com.

Im running it with miller diesel plus stuff in as apparently it reduces the unburnt fuel and black smoke emmisions you can get.

Im not after power, however if it will return 75mpg then your talking, especially at todays prices.

I will get back to you when the fuel light comes on and let you know the results (on mpg, when i want a faster car ill buy one)

The jag diesel also has around 500Nm of torque - which is more than an F1 car produces. That is what 3 litres an two turbos gives you (as well as the good mpg).

Torque is generally what you want in a road car, not outright power (only available at full throttle and very high rpms), so in that case the jag engine is a pretty good bit of kit.

The jag diesel also has around 500Nm of torque - which is more than an F1 car produces. That is what 3 litres an two turbos gives you (as well as the good mpg).

F1 cars spin to 20k revs, they don't need a high torque figure. My car has way more torque than a f1 car too. Hot hatches do these days. Meaningless stat that.

Martin does vans - www.vantuner.com

and does not over estimate your power increase.

Anyway, big downside is insurance - I declared it and my premium doubled and most insurers will no longer touch a modified car - so it gets harder and harder each year to find anyone who will quote (other than specialists who charge a small fortune).

You aren't looking hard enough. Difference between my old standard car (~225bhp) and after I'd tuned it (~290bhp) ended up being a big fat £0. And it wasn't a small fortune either. Maybe £500 fully comp.

What's the point? The last time I drove in the UK all the much, much, more powerful vehicles than the one I was driving seemed to achieve was a zap of gratuitous acceleration before braking as the gap to the vehicle in fornt diminished. A sort of "I'm a frustrated prisoner of this metal box and this trafic saturated road" statement.

Or, there's the thrill of booting a car from standstill up to 60 in 4.8 seconds. It's fun. I'm a frustrated prisoner in a metal box when I'm in the missus' Ka.