Dang interesting.
I hope no one from EHI corporate reads these forums....it'd be easy to find out who was on duty that night at BOS that rented out a Q5 for a 23 day reservation....
Honestly, this works well in Vegas for their hotels (where its basically an open secret) but I would not try this for rental car agents....it puts the agents in a tough position and I'm sure they are violating their employment contract by accepting these level of bribes essentially....usually I try to ask politely.
I would imagine it is very difficult to do an exchange in the middle of a one-way rental (I asssume?)...say if you stopped at another airport location and tried to do an exchange and see if their aisles had better vehicles?