Cars use an average 35% more fuel than the manufacturers claim, and those which are said to be most efficient are among the worst offenders, according to research carried out on behalf of Nos television.

The main reason is that manufacturers use officially-approved testing methods which fail to reflect real driving conditions and have not changed in decades, critics say.
The broadcaster bases its claims on research by Travelcard, a company which provides petrol station smart cards to the business car market.
The 400,000 cars in the Netherlands which use the Travelcard system were found to have used 402 million litres of fuel last year. However, based on the manufacturers’ estimates, this should have been 290 million litres, Nos says.
Carbon dioxide
‘This mounts up to an extra cost of several hundred euros,’ Travelcard director Jan-Reint Vink told the broadcaster. ‘We are also emitting more CO2 than expected. Whoever believes the manufacturers claims is mad.’
‘You can only approach the official estimates if you drive constantly at 80 kph and sit behind a lorry,’ Vink said. ‘That is not normal driving behaviour.’
Some cars which on paper are among the most economic to drive use some 45% more fuel than the official estimates.
Tax breaks
VVD parliamentarian Helma Neppérus said a reaction that a new method needs to be devised to calculate how much petrol economy cars use.
Cars with low CO2 emissions are subject to hefty tax cuts in the Netherlands.
Neppérus said she planned to ask junior finance minister Frans Weekers to look into the claims.
Junior infrastructure minister Wilma Mansveld also called for change, Nos television said. The issue has already been raised in Brussels and the Netherlands is at the forefront of efforts to devise a new system, she said in a statement.
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