What best describes the changes in kinetic and potential energy as the car travels from point a to point b?

Car converts chemical energy to mechanical energy in the engine, by combining carbon in the fuel with oxygen from the air to create carbon dioxide that goes out of the exhaust (hydrogen in the fuel is also combined with oxygen to create water vapour). 
The heat generated by these chemical processes drives the piston, the crankshaft and the car. 

The mechanical energy is transferred into kinetic energy as the car moves forward, and into potential energy if the car climbs a hill. 

When the time comes to stop, the kinetic energy of the car is converted into heat by friction in the brakes.