The fleet manager for a state police agency wrote that the best time to trade a car is just before the first major repair is needed (new engine or new transmission).
That's easy for him to say, he's got hundreds of similar vehicles being driven in similar usage and he can probably predict, most of the time, when that big repair will be needed.
Our family cars get driven until their condition and repairs become annoying, with Toyotas that's usually something like 15 years (Chicago salt) and 100k+ miles.
We gave up on GM products decades ago except for Corvettes, which you might consider more toy than transportation. But we actually put more miles each year on the 'vette than our two other cars, because we use it for looong road trips. Great fun, but a maintenance PITA.
We've bought 3 new Corvettes in the last 15 years, don't abuse them, and things (usually little but annoying things) break faster than we can fix 'em. We always get the extended warranty, which is usually a poor deal but on Corvettes they have been the best "investment" we ever made.
