From SMS Power!

Cheats: Out Run (アウト ラン)

Invincibility

In the main menu, put the cursor on the 1 Player option and press +++. A sound will confirm the code. Now, the game will not end when the time runs out, and the car won't crash against other cars or any other obstacle at the sides of the road.

See the main page for Out Run (アウト ラン)