Good points here. If you have another hotrod, the 35D might be a good choice - if it had AD the choice would be tougher. I wouldn't be without AD in the X5 - it is that good.

If you don't have a hotrod, the 50i is a pretty good one for also being an SUV! I have a 2011 501 with AD and it is a bit of a monster (I mean this in the very best way). And, have you heard a 50i? I mean, this baby's sound is intoxicating, which, wouldn't mean much if it didn't perform like it sounds, but it DOES!

All the best

__________________
2011 X5 Xdrive50i Sport Package AD
2013 Touareg TDI
2012 Ford F250 Super Duty Powerstroke
1997 BMW M3 Sedan
1995 BMW 540i 6 Speed

Retired:
2008 Acura MDX (good car - yawn)
2002 M5 (I will miss this car forever)
1999 M3 (fun car X2)
1992 325IS DINAN (fun car)
1987 325IS (fun car)
1986 325IS (fun car)