Most RC cars are about as hackable as it gets already. You can drop an Arduino in between the receiver and the motor controller/servos and drive them however y

Most RC cars are about as hackable as it gets already. You can drop an Arduino in between the receiver and the motor controller/servos and drive them however you want with simple PWM signals. 3x3 feet is enormous, though -- you could try looking for sites that sell BattleBots starter frames, depending on the terrain you want to tackle. Here's one: http://www.battlekits.com/ http://www.battlekits.com/