If you really want a power-dense engine, teh two stroke opposed piston opposed cylinder is an interesting option.[0] As for range-extending trailers, Tesla cof

If you really want a power-dense engine, teh two stroke opposed piston opposed cylinder is an interesting option.[0] As for range-extending trailers, Tesla cofounder J.B. Straubel had it right. The last time I linked to his "pusher trailer" the response was surprisingly close-minded for HN. The reasoning was (paraphrased) "I don't believe it because I don't trust the builder that it works because I don't believe it."[1] [0] https://idaoffice.org/posts/rebirth-of-opposed-piston-engines/ https://idaoffice.org/posts/rebirth-of-opposed-piston-engine... [1] https://news.ycombinator.com/item?id=20747218 https://news.ycombinator.com/item?id=20747218