A free program for Android, by Ultra Mad Entertainers.

Offroad 4×4 Driving Simulator is a completely free game for Android devices. It lets you build and drive your own off-road 4×4 vehicle. You can collect car parts and build your own vehicle, and drive freely in a massive open world.

This is one of the best off-road games for Android devices. It lets you do all the driving and build your own vehicle. It has a very simple interface, easy-to-use controls, and realistic physics. It is completely free, and it is developed by a team of developers that are very good at making games. 

You can choose between three modes.