Penny Racers 

More points and Class B 
Earn a metal on each level in Class C. This also unlocks better weapons. -From: ImDaMan111@aol.com

More points and Class A 
Earn a metal on each level in Class B. This also unlocks better weapons. -From: ImDaMan111@aol.com

Unlimited points and Class AA 
Earn a metal on each level in Class A. This also unlocks better weapons. -From: ImDaMan111@aol.com

Hints 
Faster parts selection 
Repeatedly tap A when the CPU is selecting a part to take from you. This may also increase the chance of nothing being taken.

Always trade parts 
Enter parts options screen and enable "Steal Parts" and "Trade/Swap Parts". Then the CPU will always trade instead of stealing your parts.

Quick start 
Accelerate just before the last light turns green.