On the cars selection screen, go to the following cars and use the gear-shifter in this order. Make sure to put the shifter on Neutral before you go to selected cars.

Item	Location
Mazdaspeed6 [GG3P] Driving School	Highlight Mazdaspeed6 [GG3P]. Move the shifter to 6-6-5-4-3-3-3-1-1-2-3-4-4-4
Nissan GT-R [R35] Spec V	Highlight Nissan GT-R [R35]. Move the shifter to 1-3-5-2-3-5-3-3-5-5-5
Subaru R2	Highlight Subaru Alcyone SVX [CXD]. Move the shifter to 6-4-6-4-6-4-6-4-6-4
Toyota Aristo [JZS161] (Taxi ver)	Highlight Toyota Aristo [JZS161]. Move the shifter to 1-1-1-2-2-2-3-3-3-3-3-3-3-4-4-4-5-5-5-6-6-6-6-6-6-6
Toyota Celsior [UCF10] (Taxi ver)	Highlight Toyota Celsior [UCF10]. Move the shifter to 1-5-6-2-1-5-6-2-1-5-6-2
Toyota Corolla	Highlight Toyota Supra [JZA70]. Move the shifter to 4-1-2-6
Toyota Hiace	Highlight Toyota MR2 [SW20]. Move the shifter to 3-2-2-3-2-2-3-2-2
Toyota Hiace (Higher ver)	Highlight Toyota Chaser [JZX100]. Move the shifter to 3-3-4-4-3-3-4-4-2-6-2-6-2-6