Full functionality requires both lane keep assist for steering and active cruise control for gas/brake. It uses data from car systems, but the model is closed so I'm not quite sure how the data is used.

The website does list what cars are officially supported. People have gone a lot further to get it on older cars, make unofficial forks, or even add radar or swap EPS.

It doesn't give you a self driving car, but I found it's significantly better than stock systems for highway driving.