Repair Kit

I am playing on PC and having a blast so far. The only problem I have so far are visual glitches such as rainbow textures and pixelated textures, but most importantly, the repair kits don't work. The description says it automatically repairs your vehicle when the damage is critical. That has yet to happen which led to me getting busted a few times and losing out on a lot of money. Is there a button for it or is it bugged?