There's been the possibility of a hybrid Smart. Unfortunately, I'm sure the reason that doesn't exist is because they'd have to make it bigger for the hybrid components. It may have been nice before hybrids caught on, but their moment of glory was very short-lived. If they'd just make it a bit bigger, maybe make a "family" version with a back seat, they could make it a hybrid. That could make some sense. But almost immediately after typing that, I realized that there was already a family hybrid Smart, and it's called the Toyota Prius.
You might like a Smart for it's strange design, so whatever, get one. I'm just saying if you're buying it for the environment, take a look at the Prius. Hell, if you don't mind getting slightly less (as in it is hardly worth mentioning the difference) milage, you can also get a Mini Cooper, which starts at a mere 1k more than the Smart. The Mini gives you a backseat, trunk, great handling, and confidence that your car is unconditionally better than everyone else's. Think about that.
Edit: Further research (see: boredom) has lead me to realize that I was wrong about several things in this post. Feel free to disregard most of it.