A "targeted" scrappage scheme could be introduced as part of the government's efforts to reduce air pollution from illegal levels.
The Department for Environment today published a draft clean air plan for consultation to improve the UK's air quality in the shortest possible time.
The plans said a targeted scrappage scheme could be used to get the most polluting vehicles off of the UK's roads. It also said central funding for local measures like redesigning roads and improving infrastructure for walking, cycling and electric vehicles could be an option, as well as reductions to motorway speed limits and expansions to clean air zones.
The government wants to reduce levels of nitrogen dioxide, which is harmful to public health and damages the environment.
According to the government's technical report, around 15,000 older vehicles (9,000 diesel and 6,000 petrol vehicles) would be taken off the road under the scrappage scheme to be replaced by electric vehicles.
Around 6,000 buses, 4,400 black cabs and 2,000 HGVs would be retrofitted by 2020.
The new plans come after the High Court ruled against the Department for Environment's last-ditch effort to delay the plans until after the general election.
Environmental groups and politicians have said the government's clean air plans are "feeble" and lack detail.
London mayor Sadiq Khan said the proposals "don't go nearly far enough to meet the scale of the challenge".
Khan said: "The government’s proposals don’t include a commitment for a new comprehensive Clean Air Act. And there’s no commitment to changes to vehicle excise duty to encourage people to buy cleaner cars.
"This is a weak plan that lacks any sense of urgency. That means thousands of people will continue to die prematurely and unnecessarily, and many more children having to live with long-term health problems."
Caroline Lucas, co-leader of the Green party, said:
The government is standing idly by while Britain chokes. This feeble plan won't go anywhere near far enough in tackling this public health emergency. We needed a huge investment in public transport, serious taxation changes and a new Clean Air Act - but none of these solutions are in the plan.
Lucas said the government has been a "catastrophic failure" when it comes to air pollution. "Half measures are not good enough when 40,000 premature deaths are linked to air pollution every year - we need bold action now."
Oliver Hayes, air pollution campaigner at Friends of the Earth, said: “The government has produced a plan that is woefully inadequate, with a breath-taking lack of detail.
“A scrappage scheme to get the worst polluting diesel vehicles off our roads is desperately needed, and it is a missed opportunity to only consult on a 'limited in scope', 'targeted' scheme. Manufacturers, who have done so much to cause the air pollution problem, should be paying the price for a national scheme, not the tax payer.”