I got the Milwaukee 2663-22 a couple of years ago for Christmas.Milwaukee 2663-22Amazon
I love it. It is probably way more power than I need, but I figured it will have other uses outside of the car. I just use it to remove bolts. I'm kind of afraid I might strip some threads. When I was deciding, I wanted something powerful enough to remove everything. A lot of the impact wrench advertise in in/lbs, and when you covert that to ft/lbs, it isn't very much.
The thing I liked about the 2663-22 is it came with two LITHIUM batteries as opposed to NiCD battery. The other thing I liked, I can just buy the other tools without batteries from the M18 line of Milwaukee and use the same batteries. Of course, they have other lines with less powerful impact wrenches, depending on your requirements.
My Name is Adam.