I do tons of car wiring and there isn't much you can't do with 3mm heat shrink, solder and decent wire strippers.
I got something similar to the Knipex one but from lidl for a few quid and it's been a brilliant tool. My soldering iron is also from there, 48W and it does some pretty meaty cables. I've also got those automatic type strippers like Dan linked too and some other older ones which are top notch.
I would recommend a depinning tool for automotive connectors, doing heat shrink with a heat gun, not lighter.
Crimping tools are nice but soldering will sort you more times than crimping, unless you work a lot with new terminals, which most people probably don't.
Get a helping hand or some wiring pliers to hold wires together when soldering.