I think there is a semantics problem here.
MB Cambridge used to (maybe still do) charge you £12+VAT per day to use their pre-registered loan cars.
Those cars are driven by staff and customers alike, get vacuumed when returned, jetwashed and rubbed down with a dirty chammy cloth.
When they get to about 6k miles they are sold - described as 'demonstrators' though they really are courtesy cars/runabouts.
So, what is the difference between their rented-out 'demonstrator' and an ex-hire car? Nothing.
How often have you seen a used MB described as a 'courtesy car', or 'customer loan car'? Most of us would run a mile from such a car due to thinking it had been abused.
Cars sell better when described as 'demonstrator' or 'ex-management'.