Current from the solenoid travels to the starter. The starter converts that electrical energy to mechanical energy which cranks over the engine. A small gear on the starter meshes with the engine’s flywheel gear. As the starter turns the flywheel, the flywheel turns the crankshaft and the pistons move up and down. This movement, along with air, fuel, and ignition, begins the combustion process. The starter is usually mounted on the underside of the engine. Automakers are incorporating start-stop technology in conventional vehicles utilizing a specially adapted starter and dedicated programming to shut down the engine when not under a load. This is a cost effective way (only a few hundred dollars to implement) to increase fuel efficiency by 3-10% and reduce emissions.