It’s just a lift. I have given many of my friends lifts places just because it’s nice to do that for a friend sometimes. I wouldn’t expect anything in return, just their friendship. A chauffeur would surely understand that it’s nicer to get a lift off a friend, just make sure to tell them as soon as possible so that they aren’t risking turning other business down. I would say go for it. I think either way either side wouldn’t really mind what you do but surely it would be nicer to get a lift with a friend, you can chat to them and enjoy the journey more. If it was me, I would take the lift. If it was me offering the lift I wouldn’t be offended either way if you didn’t want to rely on me etc. and same if I was the chauffeur, so long as you inform the driver asap.