How do I go very fast after I use the car? for me I just have the normal walking speed and woundered how to move fast like that?

Use the speed boost thing, run to the car while holding shift and then once you click on the car let go of shift, once the cutscene ends you will go super fast.

I know I'm 8 months late, but the speed boost happens because I screwed up BAD!

On the Godly Games scene I set the player speed to 100 (I don't remember exactly why) and I guess I never set it back.

Now I'm a little hesitant to fix this because it's been used in some speedruns and I don't want to mess up the leaderboards n such.