Everybody cheats on fuel consumption

[MercedesDriver]

https://www.transportenvironment.org/publications/mind-gap-2016-report

 

[Deleted member 65149]

Rubbish. I get 73mpg from my SL63 and the CO2 is 105g/km.

 

[Tim203]

Rubbish. I get 73mpg from my SL63 and the CO2 is 105g/km.

And that's round town

 

[Giantvanman]

"Mercedes once again tops the list of Europe’s car fuel economy cheats, T&E’s 2016 Mind the Gap report reveals. The Mercedes A and E class are the worst offenders consuming on average 56% more fuel on the road than claimed in the sales brochure."

VW were caught out as emissions cheats and now MB are fuel economy cheats it seems.

 

[whitenemesis]

MB should pride themselves in producing a vehicle that excels at the prescribed, controlled official laboratory tests.

Anyone who believes these tests in any way represent real world economy is deluding themselves.

 

[markjay]

The Daily Mail always had a way with words:

http://www.dailymail.co.uk/news/art...se-54-cent-fuel-road-claim-does-car-rate.html

 

[markjay]

It is a myth that such a thing as absolute fuel consumption figures exists.

The actual fuel consumption of a car depends on very many variables, including tyre pressures, make&model of tyres, tyre wear, type of road surface, number and weight of occupants and vehicle load, wind, electrical consumers in operation, windows rolled up or down, ambient temperature, barometric pressure, fuel quality, etc etc etc.

Then there's driving style, use of gears, and road conditions (speed bumps are a major factor negatively affecting MPG). Is it a straight or bendy road? Is the vehicle often driven uphill? Is the vehicle mostly used for short journeys? How long does the driver warm the engine? Etc.

But the real killer factor is congestion and traffic lights. When a car is stopped in traffic the fuel consumption figure is... zero (0 miles per gallon). Even with stop start technology. Not to mention that some drivers keep the engine running while waiting at the roadside for a passenger (and not just taxis).

And that's where the entire concept of absolute 'real life MPG figures' fails. Or even a meaningful average (i.e. one with low deviance). There is no such thing. MPG varies on a case-by-case basis. The only way to have any comparable figures is through strictly-controlled lab testing. Which is exactly what the industry has rightly been doing for years, at the protest of ignorant consumer organisations and car magazines.

Perhaps a better way of dealing with this issue is by dropping the concept of MPG altogether and using an efficiency rating scale similar to other industries, e.g. on a scale from A to G etc.

This will make it easy for consumers to compare cars' fuel efficiency without developing false expectations. This will also finally see the end of all these alarmist news articles.

 

[Deleted member 65149]

^^ Exactly. That's why I always chuckle at the posts in here about the MPG people are getting from their cars as if the figures mean anything to anyone else. I've even replied with figures I've achieved, to demonstrate the pointlessness of it all, but that goes straight over the top of most heads. It's just one of those things that people like to talk about.

 

[Alex225]

Funny thing is I can remember when in my late teens/early 20s talking to my granddad about MPG figures as he was always a big car fan.

I remember him telling me that cars never see the figures they claim in the brochures and this was probably around 2001. So I've always assumed that if a car shows 50mpg it'll be lower than that in the real world, rather than in a lab test.

I suppose the biggest cheek of manufacturers is the whole set up whereby a car detects the scenario and goes into 'test mode'. Not so much for the economy but the emissions as there's a bigger picture beyond just cheaper tax brackets, as in the environment.

It seems though, that reading snippets of info here and there, that the change to diesels, then to smaller forced induction engines etc. is all a massive heap of b*llocks!

 

[dejongj]

I was actually worried when I 'achieved' these figures that Mercedes AMG would contact me and take back the car, as surely I'm not worthy. Also found it funny that the scale doesn't seem to go higher than 40

 

[Mactech]

MB should pride themselves in producing a vehicle that excels at the prescribed, controlled official laboratory tests.

Anyone who believes these tests in any way represent real world economy is deluding themselves.

Quite right!
Engineers have been set regulations which makes the tests repeatable. They engineer cars which excel in these tests. Wether that makes the car much better in the real world with billions of different conditions and driving styles is debatable.
Cars are now 'cleaner'....but only in the certain parameters which the engineers have been asked to measure. It's the ones that are not measured that are beginning to worry the anti diesel lobby.
I reckon that some of the manufacturers have been using some of their motorsport engineers to help on emissions and fuel economy. They are hard wired to take regulations to the very edge of the envelope to gain an advantage.
'Spirit of the regulations' is a long outmoded phrase and engineers work to the letter of the regs only.
The same applies to the crash tests....cars are increasingly getting 5 stars..they are great at passing the set tests...some are even safer on the roads too
Anyone who thought VW was the only one involved in taking advantage of the badly written and ill conceived tests was, as you say, deluding themselves

My Audi is currently getting over 800 miles on a tank of fuel, unless of course both google maps and the mileage counter on the car are in collusion and moving places around in this country

 

[artyman]

Perhaps a more realistic figure could be established by the government obtaining the three months fuel purchased and distance covered from the first 100 models purchased then that average figure then becomes the statutory consumption figure. No chance of fiddling. The fuel costs of the 100 motorists in the test to be paid for by the manufacturer. The manufacturer would have to include this figure in all publicity and subsequent owner manuals if consumption was more than that stated in the initial print run. Rather than face costly reprints they may just put realistic figures in to start with.

 

[Mactech]

The problem is the word 'realistic' Realistic for who? Hypermilers, city centre dwellers? Lead foots? Miss Daisy?
Are the 'first 3 months' in summer or winter?
How do you stop the manufacturers 'placing' the first few cars?

I actually find manufactures figures quite realistic, but then I understand how they were generated and do mostly long runs.
Realistic for a hilly country dweller doing just short school runs in the winter is not going to be the same for me

If cars were not taxed on emission and fuel economy figures, there would not be the same profit incentive for manufactures to invest in 'for most unachievable' economy figures.

Maybe the answer lies in 'managing expectations' and education.....but that is probably not going to sell cars

 

[geraldrobins]

MB should pride themselves in producing a vehicle that excels at the prescribed, controlled official laboratory tests.

Anyone who believes these tests in any way represent real world economy is deluding themselves.

Personally I have found them to a good representation of what they are, which is lab tests on a rolling road. When I was doing reasonable mileage I was within 10% of the combined figure and measured over 3 years and about 45k miles.
However they are of more use as a comparison of different cars.

 

[gaz_l]

I bought a 5.5 litre V8 in full anticipation of lousy fuel consumption and I haven't been disappointed.

Cheers,

Gaz

 

[whitenemesis]

I bought a 5.5 litre V8 in full anticipation of lousy fuel consumption and I haven't been disappointed.

Cheers,

Gaz

I went from a C270CDI with ave 40mpg and 180bhp to a CLS55 with ave 20mpg and 467bhp

Over double the output for double the input, not lousy IMHO

 

[Mactech]

Well I've gone from a Full Fat Range Rover to an Audi A6 Event Ultra.
The Audi has similar internal space, refinement and performance to the RR.
But...it goes twice as far to the gallon, weighs a ton less and does not have the aerodynamics of a town hall.
I can't see over hedges so well, but that is offset by paying £30 road tax instead of £500.....and if it ever snows here again, then I'll suffer the defender for a day
Call me a skinflint, but I like it

 

[zipdip]

Well all the car manufacturers claim more MPG than you can get in normal driving,it is nothing new,not quiet on the same scale as VW cheating,what I will say is that the newer engines have made big gains in real MPG.

 

[markjay]

The same argument applies to EURO NCAP crash testing.

The reason so many cars achieve 4 and 5 stars these days is simply because cars are now designed to perform well under the very specific NCAP test conditions.

But it's anyone's guess how well will a 5-star EURO NCAP car actually protect its occupants in a crash scenario different to those tested.

The consumer has no way of difrentiating between cars that were developed from the ground up with safety in mind, and those that were merely patched-up to achieve a high score in the particular NCAP certification.

 

[190]

What I want to know is where did the real world data for that report come from. How do you produce comparable real world data across all cars and manufacturers. I don't believe it's possible.

Lab tests may be nonsense but at least it's repeatable nonsense.