Why a three-wheeled vehicle?
The easy answer is because it is less expensive to design and innovate with a three-wheeled vehicle. The DOT classifies trikes as motorcycles that do not need a motorcycle permit because they do not lean. The comparison in cost is striking: a 4-wheeled electric car design was recently documented to cost $25 million. We can design, test, and build our V1 concept vehicle for under $2 million.
The concern always raised is about stability. Trikes can be very stable if designed properly. The trike you played on as a child was built very simply, but not very well: it had one wheel in front and a very high center of gravity. The result of this arrangement is that any child above the age of 8 can tell you that if you turn a trike while going fast, the trike flips on its side and you fall down. Our design puts two wheels in front, places a majority of the mass on those wheels and has a low center of gravity. This provides for excellent traction and will encourage the vehicle to spin out rather than flip out, if the driver loses control. This is how any sportscar is designed.
There have been many different types of production three-wheelers over the years, all the way back to the beginning of automobiles. If you want to delve further, this link is good: 3-Wheelers.com.