Yes. I always ask, but LHR find various ways to fob me off, such as giving me an auto Golf with SatNav once and claiming that because it was both an auto AND had SatNav that it was a double upgrade over the manual golf that I had reserved, or telling me that PC upgrades were on a case-by-case basis that required the approval of the branch manager and he wasn't available, and my favourite was when they charged me for an upgrade before (when I argued at the time of returning the vehicle it was claimed that the Presidents Club meant I was "allowed" to pay for a double upgrade rather than have to accept the original class - in the end I got the extra back in vouchers from the Avis Preferred email team).

This time around, I was told that PC upgrades were not mandatory and it was Christmas, but if I needed more seats they could swap me to a 7-seater Seat/VW free of charge...