Originally Posted by BMWenthus

I've owned both, hands down the 4.8is is much better. There are a number of key differences.
1. Exterior refresh
2. Panoramic Sunroof
3. Rim design
4.Power close of the rear hatch, my 4.6 rattled until a TSB addressed the issue.
5. X drive which makes the SAV much more agile in the turns, I can even get my rear tires to drift out when pushed.
6. Much throatier sound
7. Dramatically better gas mileage (double Vanos)
8. Adjustable height suspension (you can get your dealer to set it to a lower level which helps lower center of gravity and handling)
9. Less harshness in the suspension, just ever so slightly smoother.
10. 4.8is finally got a transmission reprogramming that dramatically improved throttle response and shifting, 4.6 did not have this issue.
11. Both were quick and responded a little differently, but have to say the 4.8is is quicker. I time my 0-60 which did get there in 6 seconds but with premium fuel with a touch of race gas and cool morning air.
12. Had both on the track at a DE event, the 4.8is definately carves better, much less understeer. Be careful thou, as good as the brakes are they can only do so much on the track, trust me on that one.

IMHO, the 4.8is is the best SAV/SUV that I have ever owned. But both are great vehicles. You should be able to get an '02-'03 4.6is in the mid to low 30's with normal miles and an '04 4.8is in the mid to upper 40's.

BMWenthus

'04 X5 4.8is
'04 911 C4S cabrio
'89 944 Turbo S track car