18 Wheeler: American Pro Trucker Codes -

Bonus parking levels:
Successfully complete each of the four parking levels to unlock an additional parking level. Successfully complete the bonus parking level to unlock a sixth parking level.

Nippon Maru:
Successfully complete arcade mode with all four characters:

Bonus trailers:
Successfully complete arcade mode with all four characters to unlock two bonus trailers in score attack mode, versus mode, and arcade mode (if the Nippon Maru is selected).

More time:
Go into the options menu, select "Difficulty" and set it to "Very Easy". Next, save the game in the options menu and return to the main menu. Select arcade mode and you will have more time in each level, until you reach into the last level and complete the game.