TOYOTA i-ROAD test driving in Tokyo
This concept is two years old. Development is ongoing, witness an appearance at the Los Angeles Auto Show earlier this month (Warning: video autostart), so it might be a real thing soon.
There are lots of three wheel cars out there and almost all of them have two wheels in front and a single wheel in the back, Harley-Davidson tricycles not withstanding. Top Gear did a bit about an old British three wheel car (a Robin Reliant) that had one wheel in the front, two wheels in the back and an unfortunate tendency to tip over going around a corner.
Putting two wheels in front gives you better stability, but if you are using the front wheels to steer as almost all motor vehicles do, it makes your car a little wider because you have to allow room for the wheels to turn (steering-wise, not rolling-wise). It also makes the steering mechanism complicated, but it's the same kind of complicated we have in all our four wheel cars, so it's not such a big issue.
The i-Road uses the rear wheel to steer. Since the front wheels aren't used for steering it means they can be stuck right on the sides of the car, which in turn means the car can be very narrow. Being narrow makes it prone to tipping over, but Toyota has fought back by teaching the i-Road to lean into the corners. So it behaves a little differently than a regular car or a conventional three wheeler, but where space is at a premium (and it's always at a premium) this might be just the thing.
Don't know why it has two doors. It seats two people, but in tandem, not next to each other. In crowded spaces though you might not be able to get out on the side you want. I'm thinking they need doors that pivot up, like a Lambo, so you can get out even when there isn't room to open a regular door. Or maybe a door in the back, or the front, like an Isetta.