Demo mode
Press B when "Press Start" appears at the title screen.

Earn Medals
Accomplish the following tasks to earn a medal:

Collect all parts.
Collect all bodies.
Collect all engines.
Complete all areas.

Use horn
Press Up during a race.

Hint: Quick start
When starting a race, make sure you have oil in your car to increase acceleration. When the pre-race countdown reaches the end of "1" press Gas to get a head start boost in the race.