A few month ago, I decided to create an Arduino driven LEGO Truck which could be controlled via a wireless gamepad...
I choosed the LEGO model #42041 because it was cheap enought for me (59euros), and it's a medium size model (not too little to be motorized but not too big for my desk ;) )
... and a clickboard motor driver for motor managing (I used a LEGO POWER FUNCTION Medium Motor w/ a special wire) then a casual servomotor for the steering
The whole system is power-supplied with a casual 5v 1A USB PowerBank (one of the same you may use to charge your phone during the day...)
and finally it's beautifull (but expensive) PS4 DualShock Wireless Controller
If that project interested you, I may be pleased to share my code...
But if you want to find by yourself : it uses