I think it's too expensive to really take off (like say the little Japanese cars in the 70's). It's got too many downsides, the obvious one being it only holds two passengers. The other is that you can get a larger and much more comfortable, better equipped and safer Honda Fit, Toyota Yaris, or Nissan Versa for a few thousand more. And after you're done driving one of those little cars you can sell it for 5 or 6 grand. The only advantage, as I see it, to the Elio is the great gas mileage, but I think gas needs to get closer to 8 bucks a gallon for most folks to consider the Elio over a more traditional subcompact vehicle.
I'm sure they'll sell some - I do see those little Smart Cars around, but I don't see them ever in the snow, which makes me think they're still more toy than commuter car.
It's got too many downsides, the obvious one being it only holds two passengers. The other is that you can get a larger and much more comfortable, better equipped and safer Honda Fit, Toyota Yaris, or Nissan Versa for a few thousand more. It's like comparing a motorcycle to a car. Why would I buy a motorcycle when a car is bigger, more comfortable, etc? Apples and oranges.
It's a car for a city-dweller, single person, commuter vehicle, around-town car, or a second, third, or fourth car. I'd love to have one as a third car. I hate paying for gas.