If the car is untaxed, you will be within your rights to move on to the next stage and report it to the authorities. If the vehicle is covered by SORN (Standard Off Road Notice), this means it should not be on the public highway and can be reported. If it's on a driveway or other private land, you will not be able to report it as 'untaxed' – even if it's your land the vehicle is on. Scroll down to see how you must deal with 'abandoned vehicles'.