Considering trading my 2002 4.4i in for M5. Just wondering if anyone here had an E39 M5 currently or in the past. I would like to know how the M5 compares to the X5 in interior room, maintenence, and reliability. I love my X5 but I've only put 2500mi on it in six months so i figure i can afford a higher performance vehicle. Thanks for any info.