Should diesel drivers be charged £800 more in tax?
There's more - Policy Exchange also think that the higher tax should also fund a scrappage scheme for older diesel vehicles. How about that?
They think that £500 million could could be raised every year through such a charge, and the proceeds could be put towards £2,000 grants for those who have older diesels to buy themselves a more environmentally friendly vehicle.
They're arguing that people who bought diesels in good faith, years ago, shouldn't be penalised for their decision. Once upon a time, they were seen as being more environmentally than normal petrol vehicles. However, things have changed and we now know about the nitrogen dioxide which comes from exhausts, which has led to a number of deaths in the UK each year, reaching the tens of thousands.
Car emissions are a hot topic since the VW scandal which found that vehicles had been cheating tests.
Richard Howard, head of environment and energy at Policy Exchange, said: "If we are to clean up air pollution then the Government needs to recognise that diesel is the primary cause of the problem, and to promote a shift to alternatives."
"This needs to be done in a way which does not unduly penalise existing diesel drivers, who bought their vehicle in good faith, and gives motorists sufficient time to respond. Instead of increasing diesel fuel duty or banning diesels from city centres, the Government should look to increase taxes on new diesel cars and offer scrappage grants to take old polluting diesels off the road."