Drivers of small, low emission hybrid cars will take the biggest impact from the reforms. Tax on some models will be up to ten times more than under the current system.
For example, drivers of cars like the Nissan Qashqai - currently tax-free - will now have to pay the £140 flat rate a year, costing them a total of £520 over the first four years.
But those with higher emissions cars could end up saving a lot. If you're looking to buy a car that costs less than £40K but has emissions of 226g/km and above, you could save up to £600 over the first five years. It could also save almost £2,500 over ten years against the current system.
If you're planning to buy this kind of car, it's worth waiting until after the reforms have come into effect. If you want to avoid the changes, make sure you register your new car by 31st March 2017.