Saving for an M5, do i get a 3.6 and go for reliability, if i can find one that hasnt been thrashed to within an inch of it's life, or should i get the 3.8, find a nice straight / clean car and risk it's engine being a future bill maker ???

Help is required, my head is at bursting point, it's not a question of budget! i want a reliable performance car!

Any one with real world experience out there?

I need info based on knowledge, not bias!

Please help, looking forward to your replies.

Mark (UK)