From The Telegraph
Consumers could be spending an average of £133 more on fuel a year than they thought they would as a report by independent consumer company Which? suggests manufacturers are misleading consumers by overstating the fuel-economy figures to make their cars seem more efficient.
They aren't overstating their fuel-economy figures. They're figures that are the results of standard tests. What the car makers do is to set up their cars in the best possible way for those tests.
The report found that only three of the 200 models tested by the company across 2013 and 2014 reached the official miles-per-gallon (mpg) figure stated in information supplied by their manufacturer, with cars falling short by an average of 13 per cent.
Yes. Because you aren't optimising cars like car makers are
In addition, the test is carried out with all ancillary loads turned off, meaning that air conditioning, heated windows and lights are all turned off to increase efficiency.
Roof rails, extra lights and door mirrors can be removed to make the car lighter and there is no restriction on the air pressure of tyres.
Like that...
As a result, Which? is calling for the European Commission to introduce its new testing procedure in two years’ time, as scheduled, despite it "facing heavy pressure from the car industry to delay the change until 2020".
It says the process "needs to be completed properly without rushing to meet unrealistic deadlines, so that it is robust".
Why? The tests work fine as they are. Every manufacturer pulls the same tricks which means that in general, comparing cars still works. Except hybrids. And if you're driving one of those, you aren't thinking much about money anyway. OK, there's that £133 but it's not like that's much of a deal breaker when you're spending £15K on a car.
If you're money-conscious you don't buy new cars anyway but let some other schmuck another driver subsidise your driving.