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Manufacturers combined fuel figures are a joke.

2K views 19 replies 14 participants last post by  Angib 
#1 ·
I have just done my first accurate fuel figure check On my 09 cooper s convertible. That is brim the tank set trip brim again and work out MPG.
Not too good 29.75 MPG. This a mixed driving a few hills on my way to work.
I have been very light on the accelerator. I knew the stated 42 MPG combined driving seemed a bit too good to be true.All the manufacturers give an impossible to achieve combined fuel figure. There should be a clamp down on it .
I expected to be getting 35 mpg so I not too far out.Trading standards should fine them to be honest. 42 mpg would be a steady motorway run in the 's' It should not be allowed to be used for the combined figure Mini use.
 
#3 ·
it is your government that specify the exact test procedure used to come up with the mileage numbers and also that demands by law that only the mileages produced by those tests can be published

it is also true that the government employees that design the test are not qualified to do so ... my evidense is the actual results the testing produces

call your local goverment rep and complain

it is the same here in the usa, the government designs the test and by law the results produced are the only mileage numbers that can be published ... our test here was so bad that it was just recently modified ... by subtracting 30% from the test results ... very scientific!

scott
 
#6 ·
I drive a Countryman SD All4 and have just reached 15,000 miles in 16 months. Interestingly my fuel consumption is now at it's best ever which suggests that a good few miles are needed to see the true fuel consumption.
Last week I did a round trip of 460 miles from South West England to South Yorkshire and back. This was about 80% motorway, 15% A Roads and 5% town driving and I returned 54 mpg which is my best ever.
I have also found that I get the best results with Shell and Esso diesel for some reason and now try to stick with these.
 
#10 ·
Fill your tyres with nitrogen
My tyres are filled with 78.09% nitrogen, costs me nothing :D

I've always been pretty good with getting manufacturers claimed combined figures.
I'm averaging 25mpg in the gen1 MCS though :( but that's due to short trips.
I recently did my old work journey (driving like a granny) and I got 36mpg :)
So I reckon 33mpg (the official figure for the gen 1 MCS) is spot on.
 
#11 ·
i hate these threads
what do you expect, you bought a convertible sports car
the tests are real world simulations, pretty much every car would be capable of getting the specified MPG, its mostly due to driving style.
But also when you spec a car up with things like 18" wheels and climate control the mpg figure become impossible
 
#12 ·
I really doubt cooper s would get any way near a combined figure of 42 MPG 50/50 town and motorway 12 months a year.I expected low 30's in this car.What I am getting at is they should not be able to use these over inflated combined fuel figures its only in recent years they have become such a lie. In the U.K the trading standards should step in.
 
#13 ·
I just did a round trip b'mouth to Manc an back. Just got the average up to 40 after careful driving (70 max nearly all the way) as I hit the car park in Salford. Coming back this morning I had to get my toe down to see the daughters nativity play and it was dropping back toward 39 slowly at 70 to 80mph. I put some more juice in half way home and used regular unleaded where the previous tank full was super, and even at 65 the figure started going backwards.

I need a decoke though, I read that makes a big difference.

D
 
#14 ·
Generally, you will never get near the quoted figures, as the cars submitted for test feature optimised engines. A batch of engines are built using optimised components ie selecting key components by tolerance measuring a batch to identify the best parts. These engines are then evaluated and the best one is submitted for government test. So your unlikely to find a road car with the same 'pedigree'.
In addition the cars submitted are 'poverty spec' to minimise the weight, and with poverty spec skinny wheels to minimise drag.
As soon as you start piling on the options, your piling on the weight...
In fairness, all manufacturers are at the same game, so Mini have to play along with it to match the market.
 
#17 ·
Yep, to repost what I said elsewhere, I have done a 20-mile run on utterly deserted minor country roads with sharp bends and 90mph straights (and they're 'only' 90mph so I can't lose my license in just one offence), so lotsa hard acceleration and braking, and over just that distance my SD managed to get below 30mpg. Mark you, an S would probably be well under 20mpg on the same route.

Even an economical car can't compensate for it being driven uneconomically.
 
#18 · (Edited)
I have a pretty decent run to and from work.. Mostly country roads, and I routinely get over 40mpg, even more on longer runs, in my r56 s. And I simply don't believe people who say the trip computers aren't accurate, when mini themselves have said it's connected straight to the engine diagnostics and records exactly how much fuel is being pumped into the engine at any one time. To double check this I routinely record my mileage between fill ups, and then work it backwards with how many litres it takes to brim the tank, and it's pretty much spot on with what the trip computer records.

It really is down to how you drive and the route you're driving on, I get good mileage going to work because I go steady and its a steady piece of road.. On a weekend the mpg can easily plummet when I want a bit more of a thrill though!
 
#20 ·
Which? magazine just published this comparison between their mpg tests and the manufacturers:


For the Peugeot 208, that 21mpg is a 35% difference!

The difference is largely explained by their different testing regime - it's all still done on a rolling road for consistency, but in the Which? tests:

Unlike the EU test:
Our urban and extra-urban test cycles are conducted from both a cold and warm start and then averaged.
Our test includes a section of motorway-speed driving.
Our mpg figure combines the urban and extra-urban test, together with the motorway test, weighted 70:30.
They note that the manufacturers and their figures are much closer for large cars and sports cars - indeed they occasionally beat the manufacturers figure - which seems to show that this effect is due to the small cars better economy at lower speeds.
 
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