I've owned a 2004 X5 4.4i and a 2004 X5 4.8is. I then owned a 2007 X5 3.0si and a 2008 X5 4.8i.

I have also owned a 2001 ML320, a 2008 ML63 AMG and a 2009 ML63 AMG

The ML and the E70 are actually both in the last 2 years of production. Sometime in 2012 (end of the year), Mercedes and BMW should roll out the new ML and the new X5.

Both cars drive great. The engine and transmissions in all my MLs were much smoother than all the X5s. Brakes felt better in all X5s, compared to the MLs. The ML brakes are great, but the BMW brakes felt better, and were a tad more responsive.

HVAC in all MLs was leaps and bounds better than in all X5s. Navigation and entertainment systems were about the same in both the BMW and the Mercedes.

The E70 looks more aggressive than the ML, although the ML63 looks really hot...it is about $95,000, so A LOT more than a I6 or V8 X5!!

The ML is a lot more comfortable, especially with Airmatic Suspension. The X5 feels rough and too firm, compared with the ML. The ML is NOT squishy, as a lot of Mercedes bashers like to say! The Lexus RX is squishy, not the ML! With Airmatic Air Suspension, you can choose Comfort, Normal or Sport. So, the ML has more suspension options than the X5!

My E70s had more electronic problems than my MLs. My ML was not perfect in terms of reliability, but my X5s were in the shop more!

Free maintenance is HUGE for the BMW. Brakes and rotors for an ML63 is about $3500 and about $1200.00 for non AMG versions. Scheduled A, B, C, D...Mercedes Services run anywhere from $200-$800+. In the BMW everything is free.

Hope this helps you!!