[Closed] Putting the "con" into fuel economy...

It all depends on how you drive. Heavy right foot?

I can get nearly 45mpg out of my 12 yr old golf gti. I rarely do though.

To get the quoted figures you have to drive extremely smoothly

Not especially heavy, I choose to drive a diesel fiesta!

After some more investigation it appears the mpg figures are calculated by the manufacturer and use rolling roads so the impact of hills is lost. Guess you can make cars slippery and efficient but there's little you can do to beat the kinetic needs of lifting a tonne of metal up 1,000ft.

It's very well known that the figures the manufacturers use (and in fact have to use) are based on the official EU tests which follow very strict conditions on (I think) a rolling road. They are very difficult to achieve in the real world. As the figures are all calculated in the same way they allow a comparison between cars rather than an exact figure.

In fact in Germany a couple of people have now sued succesfully after new cars failed to meet the figures.

I didn't think there would be any in there getting higher mpg than advertised, but a few of them do. 11.6mpg less than advertised is pretty bad though for the kia

My german's not too good but looks like that was mercedes and the claimant got 2500 euros off the 62,000 list price.
[url= http://www.spiegel.de/auto/aktuell/0,1518,594397,00.html ]Merc gets sued over mpg[/url]

Suggestion seems to be that new cars are up to 20% under-achieving which brings mine into line especially if I add 5% for air-con.

And another thing. The manual suggests that if I live in a city and never go over 50mph I should pump my tyres up to 45psi to save fuel. Wheres that exploding tyre fat bloke picture when you need it.

Got a VW Caddy 3, drive it with economy in mind and getting pretty much what the VW blurb promised.Can't complain much about that.

Prius worst. Clarkson was right then.

20 odd to the gallon in my beast! 👿

Also Clarkson is right the Prius is cr*p.

Flintstones cars is what we all need!

The official figures for mine actually say stuff like with 38.6 and 60.1mpg for urban and touring respectively.

That works about about 50.4 which is bang on what I'm on after about 5k. I've had it up to 55 regularly till I started having to drive through town more.

Then again I'm relying on the on-board comp. Have never bothered getting a calculator out - life's too short.

Prius worst because people insist on driving them on the open road. They're a town only car otherwise it's a small engine pulling a huge weight. Good to see the Avensis betters the claimed mileage. With a careful light right foot I used to get 50+ from the 2.0 litre version.

Skoda Octavia pretty close. Which is what I've got. [smug grin]

My Vectra is quoted at 45mpg. I get down to 45mpg if abused or used in town. Usually nearer 50mpg.

I've not looked at what is in the EU cycles but most rolling roads can easily simulate the energy requirements of going up and downhill.

The EU fuel economy drive cycle does involve driving on a rolling road, but this includes some hills and accelerating from rest a couple of times. However, this is done without air con, with tyre pressures at the set limits (and sometimes on the lowest rolling resistance tyre option), with correctly set loadings for an unloaded vehicle without options (the spare wheel is now an option on many cars for this reason) (take all the crap out of your boot for a start), and other settings optimised. The manufacturer cannot publish figures that cannot be achieved, and this has to be certified by the VCA, however, on the open road, you will have to drive VERY conservatively to achieve them (and forget taking passengers, a boot full of gear, bike on the back etc). Most people will get somewhere near (to within 10-15%), but only a small handfull will get there. Bear in mind that even driving into a headwind will have an effect.

And I agree, a Prius is false economy on normal roads - it is just lugging round heavy batteries and motors and never using them. Only driven by people who are "environmentally friendly" (and if you told them that digging holes in your back garden would save the planet, they would dig holes....)

Our old Corolla only ever achieved that, & in fact a couple of mpg more, on a long steady run. "Normal" driving = 33mpg.

I have a newfound interest in MPG following buying [url= http://www.appcubby.com/gas/screenshots.html ]Gas Cubby[/url] for the iPhone, which graphs actual MPG.

I'm [u]averaging[/u] 40.3mpg at the moment in a 16 year old car designed over 50 years ago that can fit two 6" bikes in it.

All this 'scrap your car and buy a new one' business is a load of tosh.

I get 30ish mpg in a fully laden 9-5 Estate Auto (petrol) , I try not to be heavy footed............. 😀

So long as the tests are done to the same standard, and everyone is doing the same test, I can't really see what the issue is.

I guess to tweak the tests so that they get closer to real life would be good, but it's a benchmark standard between manufacturers. And that's a good thing? No?

A benchmark standard between manufacturers would be good if the results produced didn't show such a large deviation between real world measurements and published test results.

It's well within 5% deviation. I think that's pretty good. No?

I guess there will always be slight differences in the figures if the manufacturers are doing the tests themselves.

In nearly 30 years of driving everything from Motorbikes to Coaches I have never achieved the claimed figures for any vehicle. Probably as I do tend to have odd bursts of driving like my hairs on fire!

Some of the figures shown must have been with a throttle limited to 1/4 travel 😉

No, the table above shows discrepancies from 0% to 20%. My own car is not in the table as the model is new and I'm getting 22%. I don't have a distribution graph of the results so can't give you the figures for the standard deviations.

Not sure of the official figures on my new Mk VIGolf but it's way more economical than my last 5 MkVs and anyone who's been in a car with me will tell you I don't drive steady.

Average about 52mpg just driving around, down to the peaks fairly heavily loaded it returned 58mpg and running down to pick the Mrs up from work a few weeks ago it hit 61mpg. Now the car is brand new too currently just under 3k on the clock so I'm very impressed.

As for wondering why you didn't return the claimed MPG, like you found out the levels are done in test conditions and I bet going to Lakes you were loaded up that said Diesels don't suffer much from heavy loads.

Golf MkV here, get better than quoted above

can get 65mpg if the motorway is slow from birmingham to home

average mid 50s but even if i'm tanking it i still get 50

65mpg that is impressive I use to get 49 max out of mine but as I said not driving steady.

So long as the tests are done to the same standard, and everyone is doing the same test, I can't really see what the issue is.

It's news to me that you shouldn't expect to get the quoted mpg in the real world, that to me is deceptive and misleading. They don't exactly shout about the fact it's calculated on a rolling road...

Digimap your 5mpg short of the real world figure on your table (I have no idea what they mean?) sugests that you must be fairly heavy footed, or have journeys that require more fuel than average

[i]It's news to me that you shouldn't expect to get the quoted mpg in the real world, that to me is deceptive and misleading[/i]

Most of them tell you in the details.

No, the table above shows discrepancies from 0% to 20%

Sorry yes - the "-3.5" is the amount below the specified figure, not a %ge difference.

But, as I say, so long as it's a standardized test...

65mpg that is impressive I use to get 49 max out of mine

tickling along at 50 in 6th gear really is rather economical. 2.0GT though which is the newer engine

[i]tickling along at 50 in 6th gear really is rather economical. 2.0GT though which is the newer engine [/i]

I bet but not what I do. GT had same engine as all the 2.0 TDi models, they've changed it on the MkVI seems far more responsive and as I say much more economical.

I can beat the official figure in my A6 Quattro by with the Cruise on.

I'm convinced most cars launched in the last couple of years have been engineered purely to do well on the standard mpg test (so they can use it for advertising), and real-world gains have been minimal.

I ran an Alfa 156 JTD for 2 years, claimed combined mpg was 42 and I never got less than that over a tank (mainly motorway but some crawling in London traffic), average about 44.

Now have a Civic, claimed 55mpg combined, actually average around the 46-47 mark - no difference in typical journeys or driving style. 55 seems virtually impossible even on long motorway trips sticking rigidly to the speed limit.

Have to say i'm dissapointed with my new Mazda 6. Modern 2.0l diesel but get nowhere near the claimed mpg. Guess i was spoilt with my old Skoda Octavia 2.0D. Easily exceeded the official figures. Had to drive it like i had stolen it to get the mpg down into the low 40's. 60mpg plus was reasily acheivable on the motorway even with the a/c on.

Yes I have noticed that my Mazda6 2.0l diesel (143bhp) only averages mid 40's MPG, though most of the longer runs are often with 3 bikes on the roof @ around 80 on the motorway 😳
I do tend to use its handy torque for overtaking a fair bit though, backed up by me chewing through 2 sets of Conti Sport Contact 2 tyres in 21,000 miles.

Drac - not loaded up for the Lakes, just a road bike inside.

Ampthill - the figure in the table is for the old model. The new festa claims 67.2mpg combined cycle so I'm 15mpg shy. Gods know how you are supposed to get the 78.5mpg claimed for extra urban driving.

Does seem that the biggest mismatches are the newest models perhaps suggesting some "design to fit test" engineering. Bit like when manufacturers used to stick odd gearing onto small hot-hatches (like the pug 105 and saxo) to get faster 0-60 by avoiding 3rd gear.

Since the difference is worth perhaps £500-£1000 over the life of a car wouldn't be that suprised to see a class action lawsuit appear in the next few years.

My brand spanking (2500 miles on the clock) mondeo 2.0 TDi Titanium averages 42.6mpg, 75% of my driving is on motorways, so the quoted fuels figures are utter bobbins

Well my old focus (1.9tddi) estate wagon was a beauty on fuel. From Mabie to Worcester it did 73.4mpg. Which was 5.8mpg more than extra urban quoted!! Most i ever got!

On commute to work, which was fun/fast country lanes i was unlucky if i got below 58mpg. On average i was hitting around 64mpg. Usually normal-ish driving, but often had some heavy foot moments.

Will be interested to see what new car will do, as quoted figures are same as focus (Seat Ibiza 1.9tdi sport)

They all do the same test, fair enough. It's a comparison after all. If you're that bothered about fuel economy get the train ffs.

Yaris 1.0. Supposed to do 42 mpg. Northumberland - Powys - Northumberland this weekend got me 53 mpg.

Its totally down o driving style, my golf goes fast or cheap, it either does 45mpg round town driving normally, 55 on a run doing 75mph or 70mpg if you slipstream lorries with cruise on in 6th gear.

Plus new engines are as tight as a ............ ill stop now!

My 1999 seat ibiza diesel is still giving me around 550-600 odd miles to a tank and its on 186,000 miles. a decade ago its mpg was one of the highest of all the cars i looked at,supposedly topping about 74mpg when driven steady and its not even a small car with a small engine.you can put the foot down, get upto speed in an acceptable time and still get amazing miles to a tank.i never expected to get 74mpg but with the claims of it being one of the best,i had to be onto a winner.I had a 1.5 diesel before it that had a similar upper end of the fuel economy that used about the same amount of fuel on longer journeys,probably because it was labouring more to get upto speed etc.

10 years on i wonder why even the smallest of cars with small engines struggle to equal the 1.9tdi 90bhp.

Digimap how many miles has your Fiesta done?