I've been told by 2 BMW Head Mechanics that the break in requirement is a myth, that being said I've done it both for my M140i and now the X3M40i. Most Modern engines are built with such precision that the 1950's break your car in gently mentality is a bit outdated allegedly, I'm not a mechanic so don't quote me
I guess it depends if the vehicle has actually been a loaner or a demo, over here if you go on a short demo its normally round a pre agreed route and you have a tech/sales bod with you so you cant rag the car, that being said I don't doubt the staff take them out for a jolly at times and expect them to have been ragged a bit..