If you had an accident in the hire car, or even had to make a claim for the reasons you made above, even if you were on the insurance of the car hir company, surely you would have to disclaim this to your insurance company when they ask "have you had any claims in the last 5 years"? I was in a hire car last year when i got involved in an accident - even though it wasn't my fault and i was on the hire car company insurance i still declared it to my own insurance company, didn't have an impact on my insurance but don't want to get caught out at a later stage.