[AlanHo]

The UK What car Magazine recently opened a web site which purports to give accurate fuel economy figures – as experienced in their road tests of new vehicles.  Hence it includes only the models they have actually road tested.

In theory – a good idea – in practice very questionable.

You select the vehicle from the list displayed – enter your driving style, annual mileage etc and it gives you an indication of the mpg you can expect.

I chose my i30 1.6 CRDi 128 PS Blue drive car,
set the parameters as :-
long week-end drives,
75% motorway,
low congestion,
economical driving,
12000 miles per year
and it predicted 42.3 mpg (6.68 l/100km) which I find more than surprising – it is ludicrous. 
My car has averaged 54.8 mpg (5.15 l/100km) in 9000 miles from new and I know I could do better if I tried to drive for economy.

Using the same parameters for the VW Golf 1.6 TDi 105 Blue Motion it predicts 52.7 mpg (5.36 l/100 km) which seems more reasonable.

So here we have a leading car magazine trying to provide more accurate figures than the official government ones – and making a cock up of it.

Have a go yourself with other models and see what you get………….grrrrrr


http://www.whatcar.com/truempg/my-true-mpg

[eye30]

Can't check for my current or old car as both are not listed

[Dazzler]

Is their an advert on their main sponsors page for VW? 

[baroudeur]

So here we have a leading car magazine trying to provide more accurate figures than the official government ones – and making a cock up of it.

But you are not comparing like with like!  Government figures use laid down procedures under laboratory conditions to produce a level playing field.
 
Their test consists of a 50 mile  test route starting with urban driving at an average speed of 15mph. This is followed by extra-urban roads (dual carriageway and motorway) at an average of 60mph, before the test concludes with another urban loop.

Your use consists of  long week-end drives, 75% motorway, low congestion, economical driving.

 

[AlanHo]

So here we have a leading car magazine trying to provide more accurate figures than the official government ones – and making a cock up of it.

But you are not comparing like with like!  Government figures use laid down procedures under laboratory conditions to produce a level playing field.
 
Their test consists of a 50 mile  test route starting with urban driving at an average speed of 15mph. This is followed by extra-urban roads (dual carriageway and motorway) at an average of 60mph, before the test concludes with another urban loop.

Your use consists of  long week-end drives, 75% motorway, low congestion, economical driving.

So - why does their test predict that my car will achieve just 42.3 mpg when it is used for long week-end drives, 75% motorway, low congestion, economical driving.

Yet my car has actually averaged 54.8 mpg over 9000 miles since I bought it which includes lots of town driving and country roads with perhaps only 50% on motorways and without me driving for economy all the time.  I would have expected their result to be much more economical than my actual - and not the other way round.

[baroudeur]

So - why does their test predict that my car will achieve just 42.3 mpg when it is used for long week-end drives, 75% motorway, low congestion, economical driving.

Yet my car has actually averaged 54.8 mpg over 9000 miles ..........................

Because it is just a prediction?  What parameters do they use to predict a consumption based on a rather wide ranging choice of options? Entering my choice of parameters gives  a "true" 45.3 mpg but that is for the current 2012 engine not mine.

My MY2011 car with the 115bhp engine has returned an average of 49.86 mpg over 14,000+ miles.  The best ever was  a surprising 59.7 mpg after a  200 mile run at between 80 and 100 mph on a mainly unrestricted German autobahn where I topped up before and after the run. Another was 53.9 mpg  very heavily loaded on French autoroutes.  My regular driving is a real mix of rural urban, motorway and long continental runs  usually returning a mix of mid to high 40s.
I haven't checked the odometer for accuracy which I suspect is under-reading.  Really must check as I live beside a motorway making it easy to do!