None of those items need an impact wrench... If you need an impact wrench for disc brakes or engine mount bolts, you're doing something very wrong.
Get a $50 Harbor Freight electric. It will last ten years and actually remove that big nut.

OP, you're better off buying a quality used unit.
Actually I have friends the the automotive business that use the harbor freight impact guys, guys have used them for years if oiled and treated right. And they used theirs multiple times a day...
I've seen the same. They outgrow HF by their third year in the profession.
Don't get me wrong, HF sells perfectly adequate tools for certain needs and individuals. Their pneumatic impacts are just fine for Harry Homeowner, their cherry pickers will work for him too, perhaps even a few years for a shop that pulls an engine every couple of months. But none of their shitty cordless stuff will ever make the cut.
I believe 95% of the reasons for using an impact tool is to save time, not to remove overly tight fasteners.
OP, you're better off buying a quality used unit.