honda experimented with an ultra low emission two stroke mor than a 320 years ago. iirc they even raced it in the paris dakar. i think it was called advaced radical combustion, or active radical combustion. there was adjustable compression on it too. then i recall queens university belfast running a project in conjunction with ford where they designed and fitted a super low emission two stroke engine into a fiesta as a proof of concept machine, it was moree powerful that the ford turbodiesel engine it replaced but better on fuel and had lower emissions than either the petrol or dieesel version. but again, it just disapeared without a trace.
