I have gotten 750i/Li's, 550GT, X6M, X5d, X5 3.0i/4.8i, 5 Series (550i,535i etc.), 3 Series(335i,335d,328i etc.), 1 Series (135i, 128i)...and generally drive them the same way as I drive my cars.
However, I do think these loaners get neglected a lot more then the company cars i.e. cars driven by the owners, managers etc.
From my understanding there are a few classes of cars
Loaners
Sales Demos
Company Cars
BMW NA/Canada Company Executive Cars
I would be comfortable with the last 2
, but for M cars I would stick with new.