With the possibility of buying a house I would not buy a new car. High insurance and a car payment can be more stressful when shopping or paying for a house. This is just my opinion but if you're not dead set on a new car avoid the instant depreciation and get some thing relatively new. There are a lot of options out there and used can put you in a better place for whats to come.
With the potential of buying something with good gas mileage get something with enough room. 4 people traveling in a small car can get old quick. Heck, anything over a few hours in the 4Runner make me wish I was driving a motor home with a minibar and TV.