Drive: 1 L motor underneath the engine.
Steering: 1 Servo motor above the rear axle.
The suspension, fake engine, and opening safety cage still work as in the original set.
My goal for this build was to make minimal modifications of the original set and not have to change the structure too much. That explains the less-than-perfect placement of some Power Functions parts, such as the slightly recessed IR receiver and exposed Servo motor on top.
This vehicle drives reasonably fast for its size, and it crawls over some obstacles like small wheels, bricks, and the like.
I decided to build the set in white (shown in one of the pictures) because I had all the parts in the right colors, and I thought it would be interesting to try something different color-wise.
The standard building instructions are a .ldr file, but I have a .lxf file at Bricksafe for people who prefer LDD. For anyone who has the original set and wants to build this mod, you can find a list of the extra parts required here.