Originally Posted by Falmouthboy
You normally find that the 'courtesy' fleet is managed by the service dept and kept separate from the 'demonstrator' fleet that is managed by sales (and taken home each night by a salesman as a company car). You can always ask the sales team if while your car is in for the day you can take an extended test drive - they can only say no (but of course if they say 'yes' you would then get the follow up sales calls etc).
Normally I only want an 'a to b' courtesy car so am quite content with whatever they give me.
Similar here, arrange a demo car 'up front' at services, get a chance to try a few latest models. My dealer knows I'll be serious with them, when buying next.
For warranty work on my 330d, I had a brand new LCI E61 535d touring M-sport, when first launched. Had it for a week, while my car was being sorted.
I only arrange a loan car when I really need one, often wait for servicing. One time needed to go across to Edinburgh while the 540i was in for warranty work, and opted for a 116i loan car for the afternoon.
A lot depends on your relationship with the garage, IMO.