The report features lines like this:
As you can sort of see in the image above (click to enlarge), manufacturers overinflate tires to reduce rolling resistance and tape over indents to improve drag, among two dozen other tricks. In short, the report describes a complex system for automakers to get the highest possible fuel economy rating (You can download it yourself in PDF). How bad is it? Transport And Environment had independent tests done, and found that those results showed 12-percent higher "fuel consumption and CO2 emissions than official figures reported by the carmaker."
When the road load test procedures were drafted 30 years ago, no-one expected carmakers to adjust the brakes, pump up the tyres, and tape up all the cracks around the doors and windows to reduce the air and rolling resistance. These practices are now commonplace.
Greg Archer, the clean vehicles manager for Transport And Environment, told the Guardian that the tricks are evidence the automakers are cheating customers and legislators because, "EU laws intended to reduce CO2 emissions from cars and vans are only being met in the laboratory, not on the road. The only way to rebuild this trust is by closing loopholes in the current test procedures, to ensure that cheaters never prosper."
"There is no evidence that carmakers are breaking any formal rules – but they don't need to."
Europe uses the New European Driving Cycle test, which is built in such a way that it results in higher fuel economy numbers than the EPA test used in the US. NEDC is also about three decades old, an updated ruleset is supposed to be introduced in the next few years. The most frustrating aspect is that, as Transport And Environment writes, "There is no evidence that carmakers are breaking any formal rules – but they don't need to – the current test procedures are so lax there is ample opportunity to massage the test results.