'Official' fuel figures v's real life

Capri

25% less than official figures :eek:

http://www.dw.de/drive-it-the-motor-magazine-2013-10-02/e-17077876-9798

Examine it! The tricks with manufactures' fuel consumption figures Carmakers advertize their vehicles with a quoted figure for fuel consumption. But drivers find those stats are often out by 25%. Drive iIt! shows what’s behind the different methods of measurement and looks at the special conditions the tests are carried out under. But who normally drives in laboratory conditions?

Stheno

No surprise there tbh

Jesus.

I always just take 10 away from the quoted mpg to see what it might really run at

Frynge

My car apparently has a maximum range of 1257ish km but I have gotten 1310km once. That was done with excessive efficient driving just to see if I could reach the max range.

Cee-Jay-Cee

The mpg or Km/l figures are really only of use in comparison to other cars, they mean feck all in everyday life.

George Dalton

This is a major pet hate of mine, given the fact that VRT and motor tax rates are calculated from CO2 figures which in turn are closely related to MPG figures. Most new-ish diesel cars haven't got a hope in hell of meeting factory quoted figures so the whole CO2 tax system is based on theory rather than real world facts. When I see factory quoted MPG figures of 58mpg for a diesel 5 Series I don't know whether to laugh or cry tbh.

Meanwhile cc taxed diesel cars which were made before it became fashionable and financially beneficial to minimise CO2 figures are more than capable of matching or even beating the factory quoted figures. Despite this they get screwed with a penal tax rate based on engine size even though their real world CO2 emissions may in many cases be better than the supposedly lower emissions post 2008 cars.

[/rant] :pac:

CiniO

Manufacturer figures for my car are:

Urban: 6.5 l/100km
Extra urban: 4.3 l/100km
Combined: 5.1 l/100km.

My average over last 15k kms is 5.8 l/100km.
I drive mostly on country roads, sometimes on motorways and small amount of small town driving. I don't try to drive economically, and I like using the power my engine delivers.

When I once really tried hard, I managed to go down to 4.4 l/100km on longer route.

So yes - obviously - manufacturer figures are better than the ones I get in real life, but it's definitely not 25%.

CiniO

CJC999 wrote: »

The mpg or Km/l figures are really only of use in comparison to other cars, they mean feck all in everyday life.

Looks like different manufacturer show more or less realistic figures, so I don't think it's good for comparison.
One manufacturer might advertise car with better fuel economy figures than other one, while in real life it's going to be the other one which really has better figures than first one.

Interslice

I can easily and consistantly get more than advertised out of mine and it's 10 years old. Seems to be a post '08 thing with european cars in particular. You still in the Honda Cinio?

CiniO

Interslice wrote: »

I can easily and consistantly get more than advertised out of mine and it's 10 years old. Seems to be a post '08 thing with european cars in particular. You still in the Honda Cinio?

Yes. I'm so happy with it, that I don't think I'll be changing in any foreseeable future.

George Dalton

Interslice wrote: »

I can easily and consistantly get more than advertised out of mine and it's 10 years old.?

Same with my 7 year old E-Class. Advertised at 39.1mpg. I very rarely see anything below 40mpg from a full tank.

New equivalent model E-Class is quoted at around 50mpg. I wouldn't expect it to be much better on fuel than my current car if I was to go mad and buy one in the morning...

unkel

Official figures are a complete travesty

How about a Porsche Panamera hybrid? 416BHP, 270km/h, 0-100 in 5.5s, yet 91MPG, 71g/km CO2

Yeah, right :rolleyes: €170 tax per year in Ireland (less than a 1l car on the old system) :mad:

It looks like for the official figures of hybrids, they allow the batteries to be fully charged, so not impacting on fuel consumption for the first few miles (the re-charging the batteries back to full is not needed :rolleyes:), hence giving test results of 0l/100km and 0g/km CO2 for urban driving. Mixed with the more realistic extra-urban driving they get these crazy green credentials

Interslice

Just watched the OP's video. Some joke that they use a dyno. I always thought it was a real course with the gizmos hooked up to the car. It all makes sense now where they get their figures. No traffic, no hills, road surface, weather, wind resistance. Just dyno resistance of their choosing.

jimgoose

But sure this was always the way. Manufacturer figures were always derived in controlled conditions while the car was driven by one of the people who designed the bloody thing. They're not lying exactly, but, well...

Anjobe

jimgoose wrote: »

But sure this was always the way. Manufacturer figures were always derived in controlled conditions while the car was driven by one of the people who designed the bloody thing. They're not lying exactly, but, well...

The NEDC test is done on a rolling road and I believe the manufacturers use computer controlled throttle inputs rather than a human pressing the pedal.

The reason there is a bigger discrepancy between the test cycle and real world figures in recent years is because of the "bluemotion", "econetic" etc diesels that have become popular because of the CO2 based tax systems - these have throttle maps and gear ratios that have been optimised for the NEDC test cycle rather than actual driving. The test figures for hybrids are even more skewed because they can run for part of the test on electric power.

Dord

The official figures for mine (1.4L Mercedes hatchback) are;
Urban 26.90 MPG
Extra-Urban 47.90 MPG
Combined 37.70 MPG

I get 30MPG in the city, and extra-urban around 45MPG. That gives a combined matching the official figures. So, not too far off quoted figures. The tax is charged by CC as its a 2002 but the quoted CO2 is 180g/Km.

Sobanek

That's why I always refer to car test to look for MPG. Manufacturer's claims are pure rubbish.

joe40

On a slightly related note how accurate do people find the mpg readings on the car's trip computer compared to actually counting the litres to fill a tank and then noting the miles done.
I am currently doing just that so should be a interesting comparison to the value from the trip computer.

Dord

Sobanek wrote: »

That's why I always refer to car test to look for MPG. Manufacturer's claims are pure rubbish.

I usually check spritmonitor.de and fuelly.com as you can see real life long term results.