Yes, but only practical to get the last few cars you really want and are willing to spend the time involved. You have to borrow a car, delete you game data, start up game in order to change cars. Save game, install updates. 1/2 hour to 1 hour per car. Repeat and rinse.
Then you have to reload 8g to improve gameplay, another 1/2 hour or more.
If you are thinking about it...Do it today and get it overwith. Arrange for friends to place wanted cars online. Get those last few untradeables looked after and move forward. This is not a daily or weekly task. Unless you don't actually enjoy or want to play the game, that is.