Big 4WD Vehicle - Locate the green question mark symbol on the map of Mission A-4. Use the inclines of the construction area to jump over a short brick wall. There should be an area with green grass and a pavement incline going up. Follow the incline, and drop down the hole to the left. Follow the nav point to the vehicle parked within the sewer and ram into it. Once you finish the level you will get the [Big 4WD] vehicle. 

Big Truck Vehicle - Locate the blue question mark symbol on the map of Mission B-3. Go up-to the showcase room where the truck is. Use the ramp that block the path. Use the Yakuza-Car for this. Once you are in the showcase room, ram into the [Big Truck] vehicle. Once you finish the level you will get the [Big-Truck] vehicle. 

Fire the Tank's Cannon - To use the unlocked the tank from [Mission B-9] press the [Y] button to fire the cannon.
Send in by Ray Lambert

Unlock New Cars 
Unlock Dragon-SPL
Complete mission A-1
Unlock Tiger-SPL Complete mission A-8
Unlock AUV Complete mission A-9
Unlock Super-Car Complete mission B-1
Unlock Yakuza Car Complete mission B-8
Unlock Tank Complete mission B-9

Unlock New Replay Filters  -  You will gain new filters when you beat the following missions: A-9, A-10, B-9, B-10 

Unlock Taxi  -  Find the car in mission A-7 (look for the question mark on the map), and hit it once. Complete the mission and the car will be unlocked. 

Unlock Vaultsafe  -  Find the car in mission B-2 (look for the question mark on the map), and hit it once. Complete the mission and the car will be unlocked. 

How to use the A cars in B missions - All you have to do is beat all the missions up to B-10 and  A-10.

More Cars:
To get more cars, look for a question mark in the mission. Go to the question mark, hit the 
vehicle, and the complete the mission.

Mission A4: big police truck 
Mission A5: taxi cab
Mission B2: armored van
Mission B4: monster truck

Get auv - To get the auv beat mission a9 successfully

Get supercar - To get the supercar beat mission B1 successfully

Alternate view - Press Down to cycle through different screen effects during game play and  replays. To unlock more effects, successfully complete missions A-9, A-10, B-9, and B-10.

Missions A-2 to A-4 - Successfully complete mission A-1.

Missions B-2 to B-4 - Successfully complete mission B-1.

You will gain new filters when you beat the following missions: 

A-9
A-10 
B-9 
B-10

Tank-90 - Successfully complete mission B-8 to unlock the Tank-90. 

Hints: 

Use any car on any mission - After unlocking all the cars 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.

Additional Hidden vehicles - 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.

Mission A-4: Police truck - Successfully complete the missions to unlock the tank. At the start of the mission, turn left as soon as you begin and follow the path until you see some road blocks. Turn left and go as fast as you can on the path leading up on the right. Get over the  wall by driving off the dirt wall at high speed. Once there you will see a drop-off. Drive the tank so you fall down it. Move forward slightly when you get to the bottom. Turn your turret to the left and press Y to fire. Make sure to hit the Police truck with your rocket. Then, return  to where you fell and press Y. The lift will rise to the top. Find the dump truck and shoot it by pressing Y. Then, make your way up to the top of that structure. Wait until you are on the inclines before you shoot the Yakuza cars.

Monster truck in Mission A-4 - 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.
Send in by Antoinette