I think it could possibly be a combination of both. I think you (possibly) may already have it made up in your mind that you're going to have to poo when you're riding in a car, so when you get in a car you automatically think you have to poo. Trust me, I know that is really stressful!
The blood isn't normal but with my experience I have lost LOTS of blood (not just a little bit) when flaring. Also, I've had uncontrollable bowel movements and countless accidents.
You should see your doc to find out what is going on in there. Blood isn't normal, but lots of "normal" people get a little bit of bleeding when they poo sometimes and don't have Crohn's or Ulcerative Colitis.
Keep us updated on how you are doing! Good Luck!