Never mind, it seems to be working on.
it was a problem when turning left with the angle going minus that was stuffing it.
I just set the start angle and it works fine now.
Now all I need to do is the characters head and im done.

I now have the cars rotation, player head rotation and now reversing.
Any idea's one how I could make something so if it hit a wall it would bounce back?
Well I know the bounce back bit.
In my script I have on a timeout if the speed is less than zero that it will slowly stop..
But how would the wall checks work for something like this?
the most complex part I know is if(onwall(x, y)){
Pretty sad eh?
To clarify it up for anyone that doesn't understand.
I am wondering how I could make something caculate if there is a wall I front of you and bounce you back.
How would you get all the on wall checks to work ^_~

Use the same math you're using to move the car to check if that x, y position is on a wall. If it is then 'bounce back'.

You can invert the angle easily by doing

invertedangle=(angle+pi)%(pi*2)

as for the power, I would subtract a little from the initial collision. Then use the same direction formula you have already been given.

Thanks for the help, il get started on the collision checking when I get home.

All you need to do is add pi to it, the sin and cos functions don't require it to be in [0, 2pi).

I just like to keep things clean. Still,thanks for the info.

I know how to detect if there on a wall, but how would I handle it?
I have tried reversing the players movement which is this.
But that doesn't work.
I think I'm in way over my head.

You're not keeping it clean, you're just overcomplicating it and adding more work for the engine. It takes longer for a scripter to read and understand your code than it does mine.

That won't reverse the direction in which the player moves, instead do what chris said and just add pi to the existing angle.

I meant variable wise, you're going to keep on adding onto your angle which will eventually become quite a large number if used for a while. Also while you do have a valid point I'm sure one extra mod and multiplication operator doesn't effect performance to the point where you'd notice on any machine. What if I wanted to see what was going on in the script and I had some huge messy number as the angle, it'd be pretty ugly to work with. Also by including mod and multiplication the angle can work with other formulas if you choose.

Also for those who don't know % is the mod operator. It works by spitting out the remainder of 2 given numbers. Eg:6%4=2, 6%5=1, 11%10=1

Update: I now have collision detection and it works.
Next up: When you fire the weapon it should put you in the car, when you press A it should place a NPC of the car on the map and allow you to press A next to it to enter.
@Everyone Thanks for all your help