2008 Toyota Prius 4dr Hatchback (1.5L 4cyl gas/electric hybrid CVT)
This is my wife and my 2nd Prius. We also own a 2004. It has 62,000 mi and has averaged 47-48 mpg combined city/hwy. I currently have 4400 mi on the new one and am averaging 52+ mpg combined city/hwy. I regularly get 54-55 mpg city by using the surging technique. Hwy mileage for both cars is 51-52 mpg going 65 (I know that's slow by todays stds) w/air conditioning on. We both like the finish of the car. And, they are fun to drive. They have an amazing amount of room inside for the size of the car. Our 6'-5" sons can sit behind us (I'm 6'-2") and have knee room. Head room is a little tight due to the slopping roof line though.
Mileage is the favorite feature. But, the overall finish of the car is great. We also have gotten to really like the gps and 6 CD player. My golf clubs fit nicely in the back. I've driven and ridden in a Civic Hybrid. Very nice but the Prius takes the technology to the next level.
Can't think of anything to improve. For an economic mid-size car I wouldn't have anything else.