Currently lending rates are 5.9% I believe. So 6.5 is not bad.
As for what would I do? Buy a car that I won't owe long term payments on. Have you considered a clean E46 M3? Those would be almost half the cost of even the lower priced E92s.
'02 ///M5 Imola Red / Imola Red '09 335i Alpine White / Coral Red