AUTOMOBILE PEDAL

An automobile has usually three pedals. From left to right:

★ operated by the left foot:

★
★ clutch pedal (except in the case of automatic transmission)

★
★ parking brake pedal, which is usually elevated above the other pedals (replaced by a hand brake on manual transmission and some automatic transmission vehicles)

★ operated by either foot:

★
★ brake pedal, which is usually wide and elevated well above the car floor

★ operated by the right foot:

★
★ accelerator:(more commonly referred to as the 'gas pedal') controls air supply to the automobile's engine. It is usually narrow and close to the car floor allowing the driver's heel to rest on the car floor.
Since the right foot is always supposed to be in use (for the accelerator and brake) there is no foot rest on the right. The left foot only has to operate the clutch intermittently (or has no function in an automatic vehicle) so a foot rest is provided to the left of the pedals.
Nowadays, many cars include foot pedals with electric adjustment, a modern iteration of a manual adjustment system available sporadically since the 1950s.