I got both and love them!!!!
The red car that you drove with Franklin to save Jimmy is Amanda's car. A couple of missions later Jimmy buys drugs with Michael and makes him take some and tells him that he took some money from his bank account and that he is leaving and taking his car.
Michael's son Jimmy changed the car when he took it when his family left him.
I don't know if you can get banned for this, but still i did it and got me a Cheetah :D