I have a 2005 roadster that when not driven the battery goes completely dead. This can happen in just 7 day's. The dealer is lost and say's that the computers on board drain it. I have friend with a bmw m3 and he say's he leaves it for long amounts of time and it alway's starts. I can't imagine it has any less computer's. The last try by the dealer was the trunk latch. HELP.