HEre is the lowdown on the diesel thingy:
The sale of new diesel cars that do not meet latest emissions standards will face a one-off tax increase in April.
It will apply to the first year of road tax, and be levied on all diesels that do not meet the Real Driving Emissions Step 2 standards on emissions.
According to experts, it means that most new diesels would be subject to the rise.
Chancellor Philip Hammond said the tax change would apply only to cars, and "white van man" was unaffected.
The tax rise will be levied according to a car's CO2 emissions band.
A Ford Fiesta or Vauxhall Astra would see a one-off £20 rise and a Land Rover Discovery a £400 increase. Cars in the top band, such as a Porsche Cayenne, would be hit with a £500 tax.
The chancellor said: "Drivers buying a new car will be able to avoid this charge as soon as manufacturers bring forward the next-generation cleaner diesels that we all want to see.