I have 2 of them. The first one is a 2006 that was one of the last actually built by Mercedes and had a Mercedes engine and drivetrain.
I purchased it from a company in Ca. that imported 1500 of them and converted them to US standards.
I just recently recived my 2008 model. It isn the one now being sold by Penske Auto group. The new models are actually built by Mercedes, but have a Mistubsihi drive train.
As far as size, the car is great. I am 6'4" and 3oo lbs. I fit fine. They both have excellent head and leg room. They both are great around town, but are subject to alot of wandering and drifting on the higway if you try to drive over 65. The heat and air work well, except in very high heat, say about 95 or more, it struggles to keep up, especiallt the 2008. The 2006 has more power because it has a turbo, the 2008 doesn't have a turbo, but shifts smoother. That said, they both shift terribly. The transmissions are set up to drop engine power when it shifts to prevent drivetrain stress and they change gears very abruptly and jerky. The 2008's were supposed to not be as rough as the 06's, but they are.
As far as gas mileage, it averages the high 30's. If your main plan is to drive around town alot, they are great. Not so much in highway driving. But they are neat looking and you get a lot of people looking at you all the time.
In my opinion, save a few thousand and buy a Honda Fit or Toyota yaris or Nissan. They all cost less, get the same mileage or better and are bigger cars that feel more stable on the highway. But if you wnat to draw attention to yourself, get the Smart.