Actually, it's not that simple with a trike. Motorcycle regulations vary from state to state, in which many states would consider a trike of any sort a motorcycle, while others might consider a closed trike as a car and subject it to the national automobile standards.
However, one electric car builder named Jerry Dycus is taking the trike approach with the Freedom EV concept. It will be able to accelerate like a VW bug(or faster, although that is still slow), top 80 mph, and do 100 miles per charge for about $15k. And it will be virtually hand-built. The downside is, he's going to be dealing with a much smaller market that is nowhere near mainstream(while the Tango might slip in there just slightly), and he's also counting on a peak oil crisis occuring soon(which with high gas prices would help get more vehicle sales). Operating cost including batteries will be about 3 cents per mile for the Freedom EV. You read that right. Three
pennies per mile. His risk is consequently MUCH higher, while CommuterCars would rather have a more secured and garunteed market, and they'd like the car to have 4 wheels to be *somewhat* paletable as a second car to most in hopes that they will later be able to mass produce it. Further, Commutercars wanted to build a performance machine, and it would have been difficult to achieve their desired performance characteristics and stability with a three wheeled vehicle, but not out of the realm of possibility.
http://www.evproduction.org/wiki/index.php?title=Freedom_EV
Corbin Motors took the three-wheeled approach as well with the Sparrow, but ran into problems when a good number of states didn't let them market their vehicles there. Further, they easily tipped over despite a relatively low center of gravity due to having three wheels and some balancing issues with handling.
The unnecessary felling of a tree, perhaps the old growth of centuries, seems to me a crime little short of murder. ~Thomas Jefferson