Are manufacturer's quoted mpg figures accurate?

I recently bought a 1.4 Vauxhall Meriva which ticked all my boxes, including a miles per gallon claim of 47. Having tested it over the first 1500 miles of mixed journeys I only achieved 37mpg. I went to complain to the dealer who, having agreed that other Meriva owners only got 37mpg, told me how these figures are calculated. Apparently, under EU rules, cars are tested over five miles of rolling road at varying speeds and the result is the only one that manufacturers can publish. Can this be right? I believe that I have been grossly mislead and feel like asking for my money back. What is your view?

Asked on 15 September 2012 by DB, Stratford upon Avon

Answered by Honest John
That's right. It's how EC fuel economy figures and CO2 for taxation is arrived at. Ignore the EC fuel economy figure entirely and refer to www.honestjohn.co.uk/realmpg that tells you the average of what drivers are really getting.
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