FPS to Racing on the fly

I am working on a game idea where the player will be able to enter and exit a vehicle while in the game. What are the appropriate steps to do this transition?

I was looking through the forums and they said something about switching gui's, but I am not seeing any type of true answer to this on the forums.

this is the code I found in the Racing demo. (.\server\scripts\game.cs)

%cl = ClientGroup.getObject( %clientIndex );
%cl.setControlObject(%cl.car);

I then implimented this into the tutorial as a bound key, specifically to switch from a fps to a car. (./client/defult.bind.cs)

function testSwitch()
{
   exec("~/server/car.cs");
   %cl = ClientGroup.getObject( %clientIndex );
   %cl.setControlObject(%cl.car);
   exec("~/client/config.cs");
}

And of course the game froze, then bombed... LOL

Any help with this would be greatly appreciated.