We too have a small car. We have a Britax Marathon for our 2 year old and LOVE IT!!!! It is a bit on the pricey side ($280), but it has very high saftey ratings. We never had any problems with it fitting in the car. We also have the Cosco Scenera for an extra seat for the grandparents to use and it works great, but it seems to not be a snug-fitting in the vehicle. It is also hard as you mentioned, but my son rides just fine in it. For our daughter, we just bought a Recaro Como and I haven't decided if I like it yet or not. She is on the small side as well 15 pounds at 9 months old. She fits great in it and rides rear-facing. However, the first few times she rode in it, while sleeping, her head would fall forward instead of off to the side. SHe only did that a few times, and now her heads falls to the side while sleeping. It is a very comfy seat and has awesome saftey ratings. But we haven't tried it in the car yet, as we have been driving my parent's van.
Hope this helps a little bit and Good Luck with your car seat search!