Here in Norway you pay the same amount regardless of driving a little Fiesta or a big v8 car. around 300£ a year. For diesel cars without an particle filter it is 350£.
Think that's more fair. Even though it's too expensive and a lot of the money goes to other things than roads/transportation.

Not right to pay extra for schools and stuff because you're driving a car.
How is this in Britain? What do they use the road tax money on?