DH has a Mazda 3. I know it can definitely fit 2 car seats comfortably. It has the biggest trunk for that size car I have ever seen. A few people can fit in it. Plus, I have never seen a glove compartment so huge. I can fit my entire arm in it.
But he gets over 30 MPG and it costs under $20k. Very cute car. I did have one, but we traded it in for the new one. I loved it, and miss it every day when I'm driving my Corolla. If I had to choose a car right now to buy, it would be a Mazda 3.