I downloaded and installed Roaring Heights today and then went back to playing in Monte Vista. In that game, I have a Sim with 6 roommates. This was my first time playing with roommates and I discovered that as long as you dismiss the sloppy ones, they are great to have around. My Sim came home every night to a clean house and leftovers in the fridge.
So, what does that have to do with Roaring heights? Well, I bought the Classically Cool Fixer-Upper Car for that game in Monte Vista and put it in the garage, thinking that I'd have my Sim work on it eventually. About a week went by before I sent her to work on it, but when she did, I discovered that it was all done! The industrious little roommates had done it while we weren't looking.
I sold it for $39,000 and bought another one. Same thing a week later - all done and my Sim didn't lift a finger. Between the rent and the car restoration, my Sim is making a great living off of these roommates.