Stat bars in Menu system?

I'm making a racing game. In the menu, the player has the ability to choose which car they would like to use. Each car has 3 main stats, Top Speed, Acceleration, and Handling. I have a GUI Box with buttons that choose the players car, and set the 3 stats for that car. There is another box beside it that should show the stat bar for those values, but it remains blank. Here is the code for the stat bars:

 function statBars()
 {
 //Handling
     GUI.BeginGroup (new Rect (pos.x, pos.y, size.x, size.y));
     GUI.Box (Rect (100,100, size.x, size.y),progressBarEmpty, "Handling");
 
     // draw the filled-in part:
     GUI.BeginGroup (new Rect (0, 0, size.x * handle, size.y));
     GUI.Box (Rect (0,0, size.x, size.y),progressBarFull);
     GUI.EndGroup ();
 
     GUI.EndGroup ();
 //Speed 
     GUI.BeginGroup (new Rect (pos.x, pos.y - 20, size.x, size.y));
     GUI.Box (Rect (0,0, size.x, size.y),progressBarEmpty, "Top Speed");
 
     // draw the filled-in part:
     GUI.BeginGroup (new Rect (0, 0, size.x * speed, size.y));
     GUI.Box (Rect (0,0, size.x, size.y),progressBarFull);
     GUI.EndGroup ();
 
     GUI.EndGroup ();
 //Accelleration    
     GUI.BeginGroup (new Rect (pos.x, pos.y - 40, size.x, size.y));
     GUI.Box (Rect (0,0, size.x, size.y),progressBarEmpty, "Acceleration");
 
     // draw the filled-in part:
     GUI.BeginGroup (new Rect (0, 0, size.x * accl, size.y));
     GUI.Box (Rect (0,0, size.x, size.y),progressBarFull);
     GUI.EndGroup ();
 
     GUI.EndGroup ();
 
 }

Handle, Speed and accl are the variables set when the player chooses a car.

This is the code called when a player chooses a car:

 if (GUI.Button (Rect (Screen.width/3 -105, Screen.height/2+30,160,20), "1971 Dodge Charger")) {
         car = "Dodge Charger";
         speed = 85;
         accl = 90;
         handle = 50;
         statBars();
     }

I can't figure out how to make this work. Any help is greatly appreciated!!!