one thing i can tell you - is that Verizon's fleet mechaincs are bought cordless Milwaukee impacts and ratchets to use. they all like them (at least in my loacation). also dont forget Milwaukee has the non-fuel impact thats rated at about 400ftlbs i think, if you think the high torque fuel model is too powerfull..
they work on everything from cars, vans, light trucks, all the way up to the big diesel bucket trucks and digger derriecks.. not to mention all sorts of trailers and equipement.
if you have no other good cordless tools, and want to start investing in some for automotive purposes, just consider want you will most likely want or need..
1/4" impact, 3/8" impact, 1/2" impact , drill, sawzall, impact driver (maybe), various lights, right angle drill, rotary tool.. maybe even a radio... all of which the m12 and m18 platform can give you.. you can buy 2 batteries from each, and combo charger, and fill in with bare tools however you see fit.. might seem like alot at first - but it goes quick once you realize that everything you buy lives up to what you "hoped" it would be..