Honestly, a parking garage. I’ve done a LOT of small car repairs, installed exhausts, simple mods, etc for people in a random retail parking garage after hours

Honestly, a parking garage. I’ve done a LOT of small car repairs, installed exhausts, simple mods, etc for people in a random retail parking garage after hours. As long as you aren’t disassembling the motor and you’re not an asshole the security guard making $12/hr driving a hoopty in the exact same boat as you is not going to hassle you. It’s a lot less fun than doing it in a proper shop with a lift and power tools, but given enough effort you can do nearly anything with jackstands, a trolley jack, and basic hand tools.