
New Cars v Old
If you've got a diesel car already then as they saying goes "don't panic"! The new levy is only on new cars registered after April 2018.
That's hardly a surprise, bearing in mind people were encouraged to buy diesels some years ago. The government wasn't about to slap a big tax on drivers who parted with lots of money in good faith.
From April though, if you are buying a new diesel, you will probably pay more road tax in the first year. It depends on the emissions test that it had to pass, so check with the dealer before you buy.
If your new diesel car is a 'next-generation clean diesel' car – which means your car is in the lowest zero-emission band – your car will be exempt. Some good news at least.
The new tax rise will apply until around 2021, by which time all new cars have to meet the tighter pollution rules. A key point in all this though is that the tax only applies to cars, not vans or trucks.

How Much?!
If you are thinking of buying a new diesel car after April 2018 that doesn't meet the emissions standard, then for a car such as a Land Rover Discovery you could be paying £1,200, an additional £400, in tax in the first year. Others at the top of the emissions chart could be facing as much as a £500 in the first year or £1,700 tax.
Will it persuade you to go electric or just to hang on to your old diesel and hope for the best? Time will tell, but one thing is certain, tax on polluting cars is here to stay.
Check out all the emissions data at https://www.gov.uk/vehicle-tax-rate-tables

The Table of Truth
May all our Jaguar emissions be low!
New diesel tax rate changes from 1 April 2018
CO2 emissions (g/km) First-year tax increase Total in first year
1-50 £ 15 £ 25
51-75 £ 75 £ 100
76-90 £ 20 £ 120
91-90 £ 20 £ 140
101-110 £ 20 £ 160
111-130 £ 40 £ 200
131-150 £300 £ 500
151-170 £300 £ 800
171-190 £400 £1,200
191-225 £500 £1,700