They are indeed buzzy, droning, and generally over-worked at highway speeds (particularly in the case of a couple of particularly lead-footed friends who regularly exceed Japan's low highway limit...lots of wide-open spaces in Hokkaido!). Not what they're made for, for sure.

Fantastic little city cars, though. Some of the late-model ones are surprisingly peppy, even though they are limited to a low power output (a 660cc three can make a LOT more than 60 horsepower...just look at Triumph's similarly-sized middleweight triples: as much as 115hp for the sportiest one). But there's no restriction on torque, so the makers have designed engines that don't make a lot of top-end power but are tuned to maximize torque, so the engines are pretty responsive. Many have CVT transmissions, so they operate right in the fat part of the torque curve.

If Suzuki would still import the Jimny (it was called a Samurai here back then), they'd sell. It would be the "Sierra" version, not the regular kei car version. The Sierra has a "big" 1300cc engine and thus doesn't qualify as a kei car (and get the big tax and registration break those cars get in Japan), but offers an option that has more grunt off-road and is a lot more relaxed on the highway.