We rent from National every 1 - 2 weeks in different cities each time. Our experiences vary from excellent (BOS,DFW,KAN) to terrible........ Vancouver BC stands out as the worst as they had only compacts or PT Cruisers on E and EExec and absolutely wouldn't let us have anything else.
The vast majority of them are very very good and that is why we've stuck exclusively with National. If you don't see what you want in Emerald Aisle go in and ask.... 99% of the time they'll let you have your pick of anything (or close to it) on the lot. It is rare that they won't accomodate not the norm in our experience.