I know this has been out for a long time now but when you go to give someone a car you don't loose it. This is how you do the glitch.
1.Save the game data onto your ps3.
2.Quit GT5 and copy the file you just saved onto a memory stick.
3.Go back onto the game and send the car.
4.Quit the game and copy the game data from the memory stick onto your ps3.
5.Go back onto the game and you and your friend has the car!
This also works with race clothing, paints tickets ect.
1.Save the game data onto your ps3.
2.Quit GT5 and copy the file you just saved onto a memory stick.
3.Go back onto the game and send the car.
4.Quit the game and copy the game data from the memory stick onto your ps3.
5.Go back onto the game and you and your friend has the car!
This also works with race clothing, paints tickets ect.