Automatic transmission

A conventional automatic shifts gears on its own, using a fluid coupling called a torque converter to smooth the connection between engine and wheels. It is the default transmission in nearly every modern vehicle.

Gear counts have climbed from 4 to as many as 10, letting automatics beat manuals on fuel economy, a reversal of the old rule. EPA transmission codes like 'Automatic (S8)' simply describe the type and gear count.