Three cylinder engines have vibration issues, they're mostly used only in the very smallest and/or cheapest cars. Usually it's better to just make a very small 4-cyl.

With regards to importing vehicles, in Canada we can (and do) bring in anything over 15 years old. Mitsubishi Delicia 4WD vans are very popular, and I see R32 Nissan Skylines about as often as I see C4 Corvettes. There are a few companies around here that specialize in importing kei cars, but I've only seen a Nissan Pao and a Daihatsu HiJet truck.