THIS RESPONSE IS FOR THE JAPANESE VERSION OF GT3 TOKYO CONCEPT.
NO you cannot transfer cars or saves FROM or TO the game.
As you can see in the pic below... during a 2player game, you are only able to select from cars that are in game only. Not from a memory card.
There are NO options to save or transfer cars. You can only save your progress.
There is a BONUS that can be unlocked that will allow you to create a game save for GT3Aspec with 1,000,000 credits to start out with.
This is to intice Japanese gamers to go out an buy GT3 ASPEC.