[onewhippedpuppy]

I have an Earthquake air gun from Harbor-Freight. Say what you want about HF, but it has enough power to do some serious damage and has lasted a solid decade without any service or maintenance. I also have a cordless impact but find that it is only useful for small tasks.

If you want to minimize strain on the hands, also consider an air ratchet and an electric driver or two. Most auto tasks are pretty light duty and can be handled by an electric driver.