Hey, let me share a strategy:
Just kill all zombies, go all in. When you killed enough zombies, you will gain an extra skill, choose dont spawn zombie at once. So go all in to car repair. Repeat it till the end.
I think your strategy is WORST. You are just going straight and trying to kill zombies while repairing car, which is SUCKS. ABSOLUTELY FOOL BrAINed StraTEGY :)))))