At the car selection screen press shift up 6X, shift down 2X, brake, view change
When You Are Racing against a human player, both hold the brake before the race starts
This car is a hidden car so it cannot be selectable from the car selection screen. However, you can unlock it with a code. You can unlock Bunta's car in versions 2 and 3 only.
Version 2:
When purchasing a new card or starting a new game, you'll go to the car selection screen. At the car selection screen, highlight "Subaru," hold down the brake pedel, and enter in "Shift Down X2, Shift Up X2, Shift Down, Shift Up, Shift Down, Shift Up." After that, press the View Change button and you'll unlock Bunta's Impreza under "Subaru."
Version 3:
When purchasing a new card or starting a new game, you'll go to the car selection screen. At the car selection screen, highlight "Subaru," hold down the brake pedel, and enter in "Shift Up X6 and Shift Down X2." After that, press the View Change button and you'll unlock Bunta's Impreza under "Subaru."
The parts of the car are the same as the Bunta model. You cannot change its parts or its color. Only power up is available.
To unlock Irohazaka Uphill, beat Takumi on Irohazaka after unlocking him. After you race Bunta (after Takumi), Irohazaka Uphill will be unlocked.
You need to beat Takumi on Expert II. You will then be given a free race against Bunta on Akina, and, after you win or lose, the credits will roll.
To race against Takumi, beat the first 24 opponents first. He should become available to race against on Irohazaka.