[elhigh]

Knowing what you want to do with it will inform your decision. I've only had a Prius for a few months now and can say that for its relatively modest size outside, it feels pretty big inside. And the trunk is pretty darned big, frankly.

Looking at the Garage page for smarts vs. Prii you see that the mileage results they whistle up aren't too dissimilar, unless you get a Plug-In Prius in which case all bets are off. But while the two cars don't get wildly different mileage results, the Prius has way more space inside than the smart.

To me, the smart really only makes sense if you commute into a city and have to find parking, and are 90% certain you won't have a passenger at any given moment.