Try and get a few mores quotes - I ended up getting 10 of them, worse was 19k!!!
I think its the lack of nav and leather and mileage that might hurt it a bit. I sold my 335i m sport with nav and leather (13k miles) 2007. with nav, leather, auto etc to a stealer that seemed desperate to get it for 23.5 earlier this month. it cost 40k ish in may 07
however could have gotten 26 private i think - but hassle! notice its at dealer now for £27850!
heresa glass valution for your car (fantastic car BTW)
BMW 3 Series
335d M Sport
3.0TD Diesel 2-door Coupe
6 Speed Automatic
Rear Wheel Drive
Year: 2007 57
Mileage: 43,000
Estimated value of your car
Part-exchange Price:
Excellent condition: £21000
Average condition: £18600
Below average condition: £16600