I built a Lego Mindstorms rover/car as a test base for different programs and test manoeuvres. I took inspiration from another build, called NXT-GT. As I did not have a lot of parts, I had make a lot of modifications. It is possibly the best car shaped design, and is a perfect test mule for any program or hardware testing. I experimented with different designs but this really was a perfect design.

It is quite large and wide though, and the three motors really weigh it down. But because the rest of the body is very light, it's the best compromise.

It is quite low, so it does need bigger, custom wheels.

Geared for speed. When geared for torque, it can climb really steep slopes

Yep, thats an ultrasonic sensor upfront, on the steering motor.

This is the best part. The NXT Brick comes off easily, only held in place by four short bars. So it is basically only a scaffolding holding the whole car together. Light weight.

Due to the simple structure, the battery pack can easily be replaced.

Only two long bars holding the front and back end together. The brick provides the extra rigidity it needs.

There isn't much scope for a fully locking differential, as the gear lag makes it difficult to control, however some locking is possible, but it barely makes any difference.

With this assembly, I can install any type of gear, and adjust the gear size, therefore ratio.

Due to the lack of parts, I had skimp on a few important steering bars. It works perfectly, but it is quite fragile.

It is a very simple steering rack, with the motor pointing down to control the steering angle. I would prefer the motor to lie vertically, and therefore make the whole car more compact, but I don't have the gears to make a differential.

The wires do make quite a mess, so its difficult to dismantle if something goes wrong.