$45,000,000
Select an empty saved game file and press B to enter the shop screen. Select a car and press B. Move the red selection box to the bottom center square and press B, Left, B, Left B, Right, B, Right, B(3), Left, B(3), Right, B, Right, B(2). The selection box should be one square to the right of the bottom center square. $45,000,000 will be available for spending.