Currently reading: New tool rates real-world fuel economy
Cash-strapped motorists can now accurately gauge how much fuel their car is likely to use

Cash-strapped motorists are now able to more accurately gauge how much fuel their car is likely to use.

A new online tool, developed by What Car?, allows drivers to access real-world fuel consumption information. What Car? True MPG has tested cars under the same conditions motorists face every day.

Until now, car buyers have needed to rely on manufacturer's figures alone. The system to determine this information is set out under European law and conducted in laboratory conditions.

The data provided by What Car? True MPG has been gathered using a portable emission measurement system once the cars' engines have reached normal operating temperature. Engineers then test the cars over a variety of roads including motorways, A- and B-roads, and through towns and villages. The data from the testing considers driving style, changes in altitude, ambient temperature and humidity and engine temperature.

The equipment measures carbon dioxide, carbon monoxide nitrous oxide, nitrogen dioxide and total hydrocarbons. From the CO2 output and knowledge of the exact fuel in the tank, the fuel consumption can be calculated with a high degree of accuracy.

What Car? editor-in-chief Chas Hallett said: “With rising fuel prices, the miles-per-gallon issue is high on every motorist’s agenda. Countless car buyers are frustrated that they don’t match the official government fuel figures.

"What Car? True MPG will allow motorists to select a car personalised to their driving needs and budget. We hope that it will become invaluable in the complex and emotional car-buying process."


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xopher78 1 May 2012

Re: New tool rates real-world fuel economy

I always use the official figures as a means of testing one car against another; not as a means of determining how much it might cost me to run absolutely. Given that, I'm happy that the figures are conducted under laboratory conditions and not subject to further variables on the 'What Car?' tests, like weather, tyre pressure, driving style, etc.

What I'd like to see is a test that compares fuel economy over a series of distances, say 10miles, 25miles, 50miles, 100miles, 200miles, 300miles. That would then help people get a good idea of how cars compare for their commute, but also when they want to go a little further afield.

Adrian987 28 April 2012

Re: New tool rates real-world fuel economy

Reticulatus wrote:
My driving style must be really bad as I also have a Mk6 Golf 2.0 TDI, but I only average 49mpg on a tankful and occasionally drop to 45mpg!

That goes to show the variability on just one (the same) model of car. For what it is worth, my Mk5 1.9TDI has the full range of capabilities, as I have proved to myself. I could bemoan the 44 mpg that I got over 450 miles - measured by brim to brim - being poor/disappointing, or I might revel in the pleasing 70 mpg achieved over some 820 miles (on one tank, brim to brim). The former was in the Winter/short journeys with little attempt at economy, the latter in the Summer with some motorway trips thrown in and more care. Different journeys, different driving style, and vastly different temperatures.

Adrian987 28 April 2012

Re: New tool rates real-world fuel economy

I find it interesting that What Car? has introduced this True MPG tool. Interesting because they have in my view been unhelpful previously in their car reviews when quoting mpg i.e. by not emphasising that the "average economy" is just an EU compliant measurement only, not necessarily having much credibility in true motoring conditions: just one such example "average fuel of 67.3 is also hugely impressive" when this is just the EU stat (for Kia Picanto 1 Air). Or "76.3 mpg will have you travelling 670 miles between fill-ups (Ford Fiesta 1.6TDCI 95). On the True MPG gizmo, the Fiesta in most favourable true conditions evidently will give you less than 65 true average economy. If you ran the 9.9 gal tank dry, that would be 643 miles then. I have little doubt, though, that some owners will be able to better 65 mpg in some circumstances.

I welcome the True MPG concept, and What Car? are to be applauded for making somethig easy to use (and I don't have a problem with Tesco providing some of the funding either). The database will no doubt grow with time too. I do find Autocar more helpful in their tests e.g. the Fiat Panda this week - the headline: "fuel economy 38.9 mpg". This is the Autocar test average, rather than the EU "54.3 combined" (which would be "average economy of 54.3" in What Car-speak). Autocar publish three figures from their own experience, plus the EU ones for comparision.

I remain of the view that people should have their eyes wide open when basing purchasing decisions on fuel economy figures, and not place too much weight on the EU figures which manufacturers are bound to try to optimise (fudge?) so they can be used in meeting EU targets and of course for advertising lines.