How bloody oomph do you need?
Milwaukee
do a 1/2" drive 18V rattle gun that is good for 1016Nm fastening torque and 1491Nm of nut busting torque!
You wouldn't need anywhere near that much torque to work on one of our cars.... @350 Nm is all your ever likely to need working on a car.
You may as well go for a battery unit as there is no buggerising about with leads to trip over and get tangled, you can use it out and about (breakdowns etc)
Aldi had one on sale here in Oz, I got one and it's good for @ 300Nm, it works fine, cheap and cheerfull too!
I've got a Bosch blue 18V and pneumatc rattle guns for serious work but I find I use to Aldi one the most, because it's always in the back of the ute with various other Aldi battery tools, I treat them as disposable I don't care as much if some vermin scumbag thief pinches them from the back of the ute.
In fact some prick lower than a snake's arsehole did indeed steal a full set of Aldi battery tools from the ute last year,
I just went out and got more, it would've hurt a lot more if they got the Bosch Professional stuff!