Fleet cars can be great vehicles. Theay are usually well maintained (at regular schedules), and when anything goes wrong with them, they are usually fixed. The problem with them is that they were probably driven like, well a fleet vehicle.

But, that could probably be said for any vehicle. If you buy a car with 30K on it, it was probably driven like a car the owner planned to get rid of it before it started to break down.

So,
drive it like it's stolen.
drive it like it's a rental,
drive it like it's a fleet car,
drive it like it's a lease return,
drive it like etc. etc. etc.