Been getting quite a few nice upgrades lately at LHR, so be nice and just ask, as I do. There was a few weeks back where they were rotating alot of their staff around, so on occasion I didn't see the usual staff that I do, but they were still giving decent upgrades. I do rent with them quite often though. Last week booked a D for a week, during easter and upgraded to either a Audi A3 or A4 avant, I took the avant.