A computer controlled, two-stroke engine with integral generator could provide either emergency charging or range extension for EVs: As my ultimately unreplaceable Tesla battery ages, it becomes more attractive to have a lightweight trailer with a 25 kW, flex-fuel, generator. Of course this assumes available and affordable fuel. Bob Wilson
What emission regulation do drones have to contend with? GM is working on a 2 stroke design that could meet emissions. https://www.autoblog.com/news/gm-is-working-on-a-modern-two-stroke-engine-that-could-make-a-comeback
Someone will come up with an alternative pack, as long as Tesla legal team doesn't slap them down. People are throwing together Toyota traction packs...... It seems kinda ridiculous trailering an ICE motor behind an electric car. Doesn't that kinda defeat the purpose??? I guess that would take care of the range anxiety issue. Out here there's a couple of business that will offer remote/rescue recharges. I believe they are around $300-$500 and 45 minute onsite time - not cheap, but the service is there if you ignore your dash warnings. I think they are currently franchising.
My understanding is emission regulations have recently changed. Final Rule: Rescission of the Greenhouse Gas Endangerment Finding and Motor Vehicle Greenhouse Gas Emission Standards Under the Clean Air Act | US EPA Some claim more than CO{2} have been revised. Living in a no testing or enforcement Alabama, who could tell? Bob Wilson
An aviation engine will need emission controls added for road use. That will add weight and likely reduce output.