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.
'12 M3 6MT Alpine White + Fox Red Extended | '09 328i 6MT Space Gray + Black