- weight of the car (lighter cars pay a lot less than heavier vehicles)
- type of fuel (CNG is taxed more than than regular gas, diesel even more so. The prices of CNG and diesel are lower though, so if you drive a lot than CNG or diesel are cheaper to run overall)
- Hybrids/EVs don't pay road tax (for now...)
There's also a variable tax on new vehicles which is based on the environmental footprint of the vehicle.
All this is pretty fair: if you're driving more you pay more tax, if you have an old, heavy or polluting vehicle you also pay more tax. Fair enough (there are even exepmtions for classic cars).Californians are spoiled though... in The Netherlands, regular gas is $7.20 per gallon.