While a few small boutique motorcycle manufacturers have dipped a toe or two into diesel engines for motorcycles, the established brands have barely ever offered even a hint of interest in oil ...

You might find a smaller diesel engine in a lawnmower, but this is as small as it gets in a passenger vehicle.

Small diesel engines can and do power boats ... Unlike a minibike, a motorcycle is made for legal highway driving. Furthermore, diesel powered motorcycles are exceedingly rare, but do exist.

[Alex] has been working on a diesel motorcycle project for a few months ... for something [Alex] describes as an industrial Chinese engine, a modded Honda Superdream, and a few Royal Enfield ...

In the comments section of Erin's post on the diesel motorcycle ... And could such an engine also be appropriate for small cars? I don't see a reason why not.