The five-cylinder engine is uncommon relative to the ubiquitous four-cylinder, six-cylinder, or eight-cylinder variants. As an odd-number engine, it certainly is in a class of just three such engines.

Combustion engines with an odd number of cylinders are not unheard of but are not particularly common, either. Honda‘s just trotted out an interesting one: A V3, so, two pistons on one side and one on ...

V4 engines are few and far between(except in motorcycles). It's the reverse situation from 8-cylinder engines, where there are scores of V8s and a count-them-on-one ...