Boris Johnson has called for all older diesel cars to be scrapped because their fumes harm Brits' health.
The London mayor wants the Government to pay the owners between £1000 and £2000 ($2000-$4000) in a national scrappage scheme.
He said millions were unfairly "seduced" into buying diesel by being told it was greener.
"I feel very sorry for them,' Johnson told the Commons Environmental Audit Committee.
"This has been a massive failure of public policy.
"Millions were told they were doing the right thing, the clean thing, the environmentally friendly thing, by buying a diesel.They feel very hacked off now they're told they are more polluting."
Johnson said a national diesel scrappage scheme would encourage motorists to switch to cleaner vehicles.
Scientists believe diesel produces more of the tiny particles and nitrogen oxides that damage human health.
• For more car news go to nzherald.co.nz/driven
It is now known that diesel fumes create a variety of long-term problems for the heart and lungs, particularly in children.
Senior scientists have even blamed diesel for directly causing the deaths of 7000 people in Britain every year.
Johnson, who drives a petrol Toyota people carrier, has already announced moves to discourage diesel cars in the capital.
In July he revealed plans for almost all diesel vehicle drivers to be charged an extra £10 to drive into Central London as part of a new ultra-low emissions zone from 2020.
Other cities in the United Kingdom are also considering a charge as they urgently look at ways to cut diesel fumes to comply with EU clean air rules.
Britain is facing £300 million in European Commission fines for repeatedly failing to reduce levels of nitrogen-dioxide air pollution.
-Daily Mail