Fuel consumption tests

They are trying to change the rules for “official” fuel consumptions. Like the recent yes-no diesel fiasco it’s another example of a politicians’ fix. They created what they thought was an equable system, then discovered they really didn’t know what they were doing. As a road tester I found out how difficult it was to measure fuel consumption accurately. Frugal little saloons gulped fuel driven fast. Gas-guzzlers were surprisingly economical going slowly.

In the 1970s legislators decreed that manufacturers had been telling lies. A formula for working out fuel consumption was no easier for an official mind to work out than mine had been. A single mpg wouldn’t do. There had to be one at a steady slow speed, one at a steady motorway speed and one in traffic. It never worked very well. A slow-speed fuel-sipper could be a gushing drain going fast. Low-geared economy cars could be disappointing in town. A high-geared one could flatter only to deceive on the open road. Introducing Urban Cycle and Extra-Urban Cycle didn’t help much.

Even officials admit the figures are obtained under specific test conditions, “…and may not be achieved in ‘real life’ driving. A range of factors influence actual fuel consumption, driving style and behaviour, as well as the environment. Different variants or versions of one model are grouped together so the figures should be treated as indicative only.”

Averaging out the figures didn’t help. Last year testers were discovered taping up car doors and windows and driving on artificially smooth surfaces to gain a drop in “official” CO2 emissions, linked with fuel consumptions. Now, according to an anonymous EU official who blabbed to Automotive News, proposals for “a new real-world testing method,” are expected this year.