auto also called motor car and usually four-wheeled vehicle designed primarily for passenger transportation and commonly propelled by an internal-combustion engine using a volatile fuel.
A bike is a small human powered land vehicle with a seat, two wheels, two pedals, and a metal chain connected to cogs on the pedals and rear wheel. A frame gives the bike strength and the other parts are attached to the frame.
A car (or automobile) is a wheeled motor vehicle used for transportation. Most cars say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people rather than goods.