LEGO MINDSTORMS Robot Inventor
This stand-up scooter has a motor to steer the front wheel and handlebars, and two wheels on the rear drive motor for balance. You can drive and steer it by remote control, or try the autonomous program that drives in a simple figure eight pattern.
The handlebars turn when it steers, as if a ghost was driving. You can also try making an action figure ride it (perhaps with minor modifications to the handlebars). Dolls or action figures about 9-12 inches (23-30 cm) tall should fit (Barbie, GI Joe, Batman, etc). Some LEGO figures can even be attached to the deck and grip the handlebar axle.