Thanks Trapdoor - I'll give it a go and see if I can figure out what wire goes where. I don't like friggin' with the car's internals when I clearly don't know what I'm doing, but I want to get this working. When you say RHS, you mean PASSENGER's side, right (looking at X3 from the front?)

Aha. No.. reposted - I see what you mean - you mean to get 12vDC from the 'cigarette lighter' socket on the driver's side...

Don't suppose you have a picture of the lead you created?