1. There's nothing wrong with having roommates. I have brought back many chicks while living with roommates. It's totally fine....unless the "roommates" are your parents. Then you might have some work to do.
2. I see some car discussion above. If you're driving her home, that's perfect. When you get to her place, say that you really need to use the bathroom and that you'll let her slide on paying you gas money for letting you up. If she says that her place is too messy, then say, "That's perfect! If your place was spotless, I think you're an OCD freak. I'm glad that you're a normal person."
3. As for "making the move" in the car, it can be great, but I personally don't think that it's a good idea to "make the move" when you're at her place dropping her off. It generally feels forced and cliche, and she'll be expecting it then. Instead, catch her off guard and in the moment - when making the move is hottest. My favorite move is what I've coined the "Red Light Entertainment." When you get to a red light, you say, "Ugh, red lights are so boring. Let's make them more interesting." She'll look at your curiously, ask how, or say "ok." Then say, "I got it!" with a smile, look in her eyes, and lean in for the kiss.