&gt; I never found out what became of this<p>That&#x27;s a common pattern in new (combustion) engine designs; there&#x27;s a lot of them being published every year, but almost none of them actually end up being mass-produced and they dwindle into silence or as just demonstration models. Why? I don&#x27;t know; the media only seems to focus on the invention and potential, not the failure (or if I were to put on my tin foil hat, the disappearance under mysterious circumstances). The only nonstandard engine that (AFAIK) ever got some leverage was the rotary wankel engine, and even that was (iirc) in just one car model.