Again, Wikipedia. My definition comes straight out of the Webster dictionary.
Your web page that labels it "Three-wheeled car" counts and not my half-dozen pages that say "Flying car"?
edit: Then again, why the need to specify "three-wheeled"? Because you just can't simply call it a CAR. Not even the government considers(considered?) it to be a car:
"Despite its size, by being a three-wheeler with an official mass below 450 kg (992 lb), the Robin could traditionally be driven by holders of a B1 category driving licence in the United Kingdom, and registered and taxed at motorcycle rates, which gives a saving of 55 GBP per year over a conventional car."
It doesn't matter for the offroad one in the slightest. You can drive it on roads as easily as you can drive a car on the dirt. You can't (legally) drive a small airplane, with or without folding wings, down the road.
So in conclusion, and after thinking about it a minute, I could eat a bowl of alphabet soup and shit a better argument than yours.