The tests examined the Golf Bluemotion, Skoda Fabia Greenline, Mini Cooper D, Honda Civic Hybrid, Toyota Aygo, Ford Focus Econetic, Fiat 500 1.2, BMW 118d, all of which are regarded as low emissions/fuel economy models.
The Golf Bluemotion got closest to its official figures in the 4Car tests, achieving 57.5mpg, only 5.3mpg short of the 62.8mpg return in the government-approved tests. Ford's special low-emission version of its best-selling Focus, the Econetic, returned 54mpg in the 4Car tests – 11.6mpg less than the official figure (see results below).
The fuel tests also revealed that claimed carbon dioxide emissions figures are unrealistic and that all the cars, which are currently in VED Road Tax Band B, should fall into Road Tax Band C.
The tests were carried out under strict conditions in order to achieve consistency. Unlike the official testing regime, which is carried out in a laboratory, 4Car’s tests were conducted on the road to replicate ‘real world’ driving conditions. And unlike the official figures, which simply combine urban and extra urban cycles, 4Car carried out five sets of tests to arrive at an overall consumption figure (see Editor’s notes).
4Car editor Tim Bowdler said: "The official test regime is too simplistic to embrace all the vagaries of real-world operating conditions and it allows certain types of car to look good – too good in fact.
"The batch of cars that we tested all claim to have ‘green’ credentials, but they are not as environmentally friendly or as economical as we've been led to believe.
"Manufacturers argue that the official tests offer a level playing field that enables potential car buyers to make direct comparisons, but they bear little relation to real-world driving. The official figures are...