If the MoT history is encouraging, look for telltale marks such as wear on pedals, marks on the steering wheel, round door handles etc.

My 207SW was a rental car for 7 months before showing up at a Pug dealership with over 13K on the clock and no service history, because it was moved on when an oil change became essential. It looked in decent nick and I bought it despite the oil change being overdue IMHO. So far I have not regretted it, and I still have it - but I immediately shortened the change interval to 7-8K miles (it's a diesel).

I’ve never seen fleet cars per se as an issue. I had company cars for years and they were all well-maintained.

As for the eight personal cars we’ve owned in 35 years, only two had private owners. We even had two ex-driving school cars that we bought at one year old knowing their history. Not for the faint hearted if you worry about abuse but one we traded in after a couple of years at a paper profit and the other is still showing as MoT’d at 14 years old and over 100k miles.

As others have said judge on condition and service history rather than whether its been on a fleet.

However despite my experience it’s probably best to avoid driving school cars. We might have been lucky but they are likely to have been subject to clutch and gear abuse. It can be hard to identify them even from the V5 as they will use company or other company names. Holes for dual controls were a giveaway on ours.