Oh, Sims and their cars. Lol. I've had them drive a car to a location, then take a cab back home. I found one of my cars in the parking lot of the science lab when I just happened to send another Sim there to fish. There it was, just sitting there. I wondered what had been happening with missing cars! I had a Sim who would take his bicycle instead of his car, too. I put the bike into the family inventory to solve that problem. The only real time I've noticed that they take a cab instead of their car is when they are taking a baby someplace. They apparently don't have car seats and can't take a baby in the car if it's just the one adult.