Tenacious D- "You can't kill the metal. The metal will live on. Punk rock tried to kill the metal, but they failed, as they were SMASHED to the ground!"
When the accelerator is pushed so far it cant move any more- in some cars it hits a metal bar, or the end of the footwell (which is hopefully made of metal).
Hence the term pedal to the metal. Obviously if you have the acceleratorall the way fowards youre gonna be gathering speed...or going fairly fast.
When one pushes the gas pedal to the floor, making the vehicle burst to its highest possible speed. Generally done on straightaways or during drag races, accompanied by a burnout.
This phrase is a combination of balls to the wall and pedal to the metal. It is used to describe the reckless courage displayed by an automobile driver who performs death-defying driving maneuvers to escape pursuing law enforcement.