In the past my biggest construction weaknesses have been with custom gearboxes and managing speed reduction in an efficient way. They always became the weakest link. So to simplify things, at least initially, I'm using three motors to power two 10 inch wheels (left and right).

The main drive motor is a full transaxle from a Kymco XL mobility scooter. I've used similar golf buggy transaxles before and they are impressively 'torquey' and reliable. Rated power is 850w, although it'll be running at around 2kw. Energy losses in the gearing are minimal, although I don't yet have a figure for this.

This big drive motor is aided by two geared Pride Go motors, one on each side. These will be running at around 800w each. These use the diffetential (in the transaxle) to be the turning/steering motors too.

A more complex set up than a single motor each side and a set up I've never tried before. Sort of like a hybrid system. It also brings in 2 levels or redundancy. If big drive motor control fails, the 2 smaller motors can keep control. If one of these fails, forward power is reduced but steering is maintained by second small motor.

Needless to say this is a brushed motor set up. I just need to work out the transmitter mixing.

The Kymco XL motor is rated to pull 330kg with a full load.