--- bmwM3.js.old        2012-11-17 21:20:42.438109157 +0100
+++ bmwM3.js    2012-11-17 21:25:43.651911123 +0100
@@ -51,9 +51,10 @@ function init_chassis(){

     this.finalRatio = 3;
     this.torqueMultiplier = 10;
+    this.maximumSpeed = -1; // speed in m/s. a value < 0 means there's no maximum speed
     //end of engine properties
-
-       this.torque = engineTorque;
+
+    this.torque = engineTorque;

     return {mass:1500, steering:2.0, steering_ecf:60, centering: 2.6, centering_ecf:20};
 }
@@ -119,9 +120,9 @@ function update_frame(dt, engine, brake,
     steering *= 0.6;
     this.steer(-2, steering);

-
-    var khm = Math.abs(this.speed()) * 3.6;
-    var wheels = Math.abs(this.speed()) / (this.wheelRadius * (2 * Math.PI));
+    var absSpeed = Math.abs(this.speed());
+    var khm = absSpeed * 3.6;
+    var wheels = absSpeed / (this.wheelRadius * (2 * Math.PI));

     var gears;
     if (this.speed() >= 0) {
@@ -140,7 +141,10 @@ function update_frame(dt, engine, brake,
         this.gear -= 1;
     }

-    var force = engine * this.torque(rpm) * this.torqueMultiplier;
+    var force = 0;
+    if (this.maximumSpeed < 0 || absSpeed < this.maximumSpeed) {
+        force = engine * this.torque(rpm) * this.torqueMultiplier;
+    }
     this.wheel_force(2, force);
     this.wheel_force(3, force);