Algodoo

ok good i downloaded it and it seems to work.

the cars have motor hinges..

you don understand, the hinges are only motors if the speed is positive or negative if its on 0 they ae in stop mode.

i used the variables "a" and "b" for this. (foget about b itsfor th other car) i said fo the little circle where you hit it when enteris pressed "onCollide=(e)=>{a=a+0.5} so once yo hit it a=0.5"
now youre thinking, who cares? but i used that to script the hinges to respon to a.
i said on the hinge for the car motorspeed={a}
so the motor speed goes whatever a is. if a=0 then the motor goes 0rpm
evey time you press enter you hit that circle which says a=a+0.5 and th motor goes a speed, a suddenly equals 0.5 so the motor says WAIT A MINUTE! A=0.5 ! WE HAVE TO MOVE THAT FAST NOW! and every time you hit enter the hinge goes up by incremens of 0.5 so afterawhile you can go 100rpm.
but heres this other circle next to it that you CANT control wihout chating. every time that one gets hit it says "onCollide={a=a-0.5}" t makes you go slower, inorder for you to accelerate you have hit youre own circle faster then the uncontrollable one does.
kinda hard to explain, but i hope this helps.

oh, and "b" was used for the bottom car, i just took all th same scripting and replaced "a" with "b"