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Why are your correspondents surprised that they can't match their car's official mpg figures?
Your letter-writers often complain that they can't match their car's official EC mpg figures. Surely it's common knowledge (or ought to be?) that these are measured while the car is driven in accordance with some sort of notional ‘typical' driving pattern on rollers in a laboratory, and, as the UK and other countries tax cars on this basis, manufacturers will pull every trick in the book to get good test results, even at the expense of poorer real-world economy. There will be a broad correlation between the official figures and reality, but a close match is probably coincidence.
Asked on 3 April 2011 by CD, Essex
Answered by
Honest John
Since cars are taxed on their CO2, and since from 2013 manufacturers will be fined if their corporate average CO2 exceeds 130g/km, it is only natural that they optimise their cars for these tests and that performance in them bears only a mild relationship to what drivers can expect in real life. The tests are conducted in ambient temperatures of 20 – 30 degrees centigrade. So obviously if the car is heat soaked overnight in a 30 degree lab it won’t ever need to go through the fuel-hungry cold start cycle.
To inject some reality, we now offer the Real Life Fuel Economy Register (www.honestjohn.co.uk/realmpg) where drivers can regularly log their real life fuel economy. Each time they do, the average for their make, model engine and transmission is adjusted and a figure is constantly displayed giving anyone a real life average fuel economy figure.
To inject some reality, we now offer the Real Life Fuel Economy Register (www.honestjohn.co.uk/realmpg) where drivers can regularly log their real life fuel economy. Each time they do, the average for their make, model engine and transmission is adjusted and a figure is constantly displayed giving anyone a real life average fuel economy figure.
Real MPG enables you to register the fuel economy you are actually getting against your make and model of car, its engine and type of transmission.
Every time you enter an average consumption figure against your car, the overall average automatically adjusts to reflect it.
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