At the main menu, highlight the "Unlimited time" option, then press L + R + Right + Z as the game loads.
Successfully complete mission A-1 to unlock missions A-2 to A-4.
Successfully complete mission B-1 to unlock missions B-2 to B-4.
Successfully complete mission A-9 to unlock the AUV.
Successfully complete mission A-1 to unlock the Dragon-SPL car.
Successfully complete mission B-1 to unlock the Super car.
Successfully complete mission B-8 to unlock the Tank-90.
Successfully complete mission A-8 to unlock the car that Tiger Tagachi drives.
Successfully complete mission B-9 to unlock the Yakuza car.
Successfully complete all twenty missions to unlock the "Music Test" selection at the options screen.
Press Down to cycle through different screen effects during a game and replays. To unlock more effects, successfully complete missions A-9, A-10, B-9, and B-10.
The hidden vehicles in the game can be found by locating the "?" on the map in four different missions. Mission A-4 has the police truck. Mission A-7 has the taxi. Mission B-2 has the armored security van. Mission B-3 has the monster truck. Other vehicles are found by completing the missions, everything from sports cars to a tank after mission B-9.
After unlocking all cars in the game you can cycle through them from both scenarios on any mission. Just scroll past one set to get to the second. Be careful, as in some missions the car you choose affects the opponent you will face.
In this mission, you have to rescue the professor from the dump truck. On your map you will see a green "?". If you can get to that location, you will find the monster truck. At the very start of the mission, you will be behind the dump truck. Go to your right and launch yourself off of that edge into the back of the truck. That is the first hit -- you need four hits total to destroy the truck. After the first hit, drive back to where you started and take the U-turn. Follow the road down to the bottom and do a 180 turn by sliding. You should now see a fork in the road. The path to the left is where you just came from. You need to take the path on the right at full speed and run into the wall. This should catapult you up to a little grassy area Once there, you need to find the blue-looking ramp up to the elevator shaft (the elevator is on the bottom floor). Do a graceful dismount with your car straight down the elevator shaft. Poke around down here to find the monster truck. When you see the truck, ram into it. You now need to get back on the elevator (press Y button to activate) and go to the top. If timed correctly, the dump truck should be making a pass in front of the edge of the end of the grass area that you are now on. Take a run at him as he goes by from left to right. You will bounce off him and back on to the grass. Put it in reverse and take another charge at him when he goes by from right to left (that should be three hits total). You should be back to where the level started. Hit him again from where you hit him the first time. He will explode and the professor will bolt for the helipad. Go towards the helipad, but instead of taking all those ramps to the top, drive around the base and find the elevator. At the top, go across by dodging the two cars attacking you and take that elevator to the top. Get the briefcase and find the helipad. Note: Do not forget to watch your time.