from 08 X5 to 02-03 e39 m5?
 

want a car with more torque, thoughts?

Go for it man, ff you don't need the room/snow capabilities then why not! I love the M5 in general. The E39 was one of my dreamcars when I was a kid, so I may be a bit biased! I hear they're the best in terms of driver involvement, kinda bummed the next gen M5 won't have a manual anymore (which I still think will continue to be fantastic cars). Best way is to go drive a few!

if you want a well maintained low mileage m5 you're going to pay up for it... if you find one that is higher mileage and maintained may be a better value but stay away from almost any and all that have a drop of deferred maintenance or have signs of abuse... the repairs and cost of ownership will most likely exceed the savings or the overall cost of the vehicle.

i owned one before, i loved it. most likely a modern classic and definitely one of my favorite cars out of the bunch i've owned. i've been tempted to purchase another and have been following the market but the ones that piqued my interest are not worth the money.

The E39 M5 is my favorite car (that I have owned) of all time. Spend LOTS of time looking for the right one and you will be very happy.