Car insurance premium for young drivers.

I'd say put your son on your insurance policy as a named driver to get the cheapest car insurance quotes because he's still a young driver but you need to do that with a company which is going to allow him to build his no claims bonus (NCB) while being a named driver, otherwise he's going to start back to square one when he takes insurance in his own name.

Also it is worth mentioning that when you son becomes an additional driver, he should not be using the car all the time as the most frequent user has to be the policyholder.