Re: Drift events & Race events with same car!?!?

You can swap cars. Go to any meetup and change your ride there (can also change handling there). Not your safehouses for obvious reasons. 

  As for changing handling you can also change that on the fly, buy entering the exit game screen (might be pause screen assuming you are playing the story) while roaming open world. I think the options are Resume, HANDLING, Leave Game.

 If you have a decent diff installed, you can change the grip/drift setting quite a bit.

 Doing this I was able to have a single car do both B and A class races, by changing the diff, and downforce settings.