Why do cars not achieve the claimed MPG figure?
Your motoring problems solved
Q. A Peugeot I test-drove recently claimed 90mpg; I managed 47mpg. Why the discrepancy?
CC, Chippenham, Wiltshire
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A. Car makers have become adept at designing to the laboratory test, which was last updated in 1997. They design cars with gear ratios and engine settings that will ensure a good result. The International Council on Clean Transportation says real-world and test figures now deviate by about 40%.
Hybrid cars can have even greater discrepancies than standard petrol or diesel-powered vehicles.
However, a new test is due to be introduced in 2017 that will more accurately reflect real-world MPG, with manufacturers forced to publish results.
TIM’LL FIX IT
Tim Shallcross used to train AA patrols to fix cars. Now he advises the Institute of Advanced Motoring — read more from Tim here.
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