A free app for Android, by Cleve Apps.

Off Road Physics Race – Hill Climb & Down the Hill is a fun and entertaining physics game that will challenge your brain, your creativity, and your motor skills. It is both a physics simulator and a construction, adventure game. You will construct, upgrade, and drive your cart – using concepts in physics. And then you must drive your cart to accomplish the mission – which is to deliver all the fruits to the finish line within a set time. Explore uphill motions and downhill accelerations – anything at all to help you accomplish the ultimate goal.

There is a global leaderboard that you just may get into… if you are up to the challenge.