very little, different trans prorgram, bluetooth, and I believe the '04 has a lower limter than the '05 (on the C&D test, they had an '04 and it was limited to like 128 if I remember correctly), but other than that its the same car

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2006 BMW X5 4.8is Lemans Blue/Beige/Dark Maple
-Nav, Comfort Seats, Heated Steering Wheel,
Rear Airbags, AUX Input
2009 BMW M3 Space Grey/Black/Carbon
-all options