The M5 and 335 are very far apart. totally different cars. If you can afford to take the hit on the 335 which you will since you just bought it. just go for it. The M5s are moving slow and you may get a good deal. I think they are doing 3.9% financing until the end of the month.

Ive been looking around for cars and have been to 4 dealers in 2 weeks. Every dealer had 1 or 2 M5s sitting on the lot that they couldnt move.
They said that the best sellers right now are the 335, 535 and 550 sports.

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Dinan M3

2006 X5 4.4i Sport Current Vehicle
2006 CLS 55 AMG Current Vehicle
2010 FORD F-450 King Ranch Current Vehicle
2012 GL 550 Current Vehicle

1999 M3 Dinan S3 SOLD
2001 M3 Dinan S2 SOLD
2002 M5 SOLD
2004 X5 4.4i sport SOLD
2007 335 XI Lease ended
2009 E92 M3 SOLD