I haven't done that tutorial, but from looking at your car action, you have two places that look like the problem:

Code:

---

if(key_w == off)
{
     ...
     ...
}

if(key_s == off)
{
     ...
     ...
}

---

These are both within a while loop that is constantly checking to see if keys are pressed. But you have these two set up so that if keys AREN'T pressed, then they do something. So when you start up your level, they instantly go into effect.

Your problem is that you're trying to make these things happen when the user "lets off" the gas, but the code executes whenever the key is not being pressed. You need to make these things happen after the key has already been pressed, and THEN the user releases. Give it a shot for a little while and if you can't figure it out, I'll help.