One of your readers letters extolled the virtue of running older cars. Like you, I remember when I was young and had little money. I ran old cars and can’t forget the grief they gave me. Never again.

I must ask your advice on behalf of my in-laws, who have a 2004 BMW 530d automatic. The car has done about 4,000, miles since being fitted with a new engine, plus turbo, because the swirl flaps broke off and wrecked the engine. The work was done by a franchised BMW, dealer and cost about £14,000. BMW, paid most of this as they admitted the engine fault was their responsibility.

My in-laws do low mileage in this car, but have no worries about the particulate filter because it does not have one. The cars runs like a dream, uses no oil, and for a big car gives astonishing fuel consumption, about 45mpg, on the motorway. Should they keep this car and run it for a few more years?