I bought an '06 Vibe (considered a small hatchback wagon) 6 months ago. I got 37 miles to the gallon when I had it on the highway. Our other cars are a 97 Odyssey and a 96 Explorer, and I was beginning not to feel safe on the highway at night - I'm often on some pretty deserted roads that don't even have cell service.
The back seats fold down so I thought it would handle the storage I needed - WRONG! It only has 2000 miles on it in six months (and that's with 1000 miles from one trip).
I still have my '97 Odyssey and end up having to use it all of the time. I love the mileage and how the Vibe drives - plus it is SO cute. But it holds nothing.
With the two back seats down I can get in a big suitcase and the dog carrier. My dad hates to ride in it - says it's too small for him (6' and 250 pounds plus he's 85 years old) and too hard to get in and out of.
If it's me, my sister, and my dad there is no room for our luggage or the dog carrier. We would each have to use one small duffel bag and not put the dog in a carrier.
My dad has a 96 Explorer - I don't like to take it on the highway as he has not maintained it very well - although it only has 50,000 miles on it. I think I may have to upgrade him to a van.