Luck, which can run out. After seven years any owner of any car can face a repair bill that is greater than the value of the car. I safely predict that, with the increasing complexity of cars and the rising cost of failures, the number of cars 7 - 12 years old will decrease every year. Failure of the electronic key and the ABS of a 2004 Nissan Micra, for example, instantly renders that car scrap because the repair bill can be more than £4000. All that said, Britain is now so broke that there are still more than 13 million vehicles on UK roads that are more than nine years old, providing lots of work for garages.