[Aloha]

I mean in current production aircraft.

It appears that most versions of the O-360 can run on mogas, or unleaded gas of some sort.

https://www.lycoming.com/sites/default/files/SI1070AB%20Spec...

Indeed, there does appear to be a 100UL drop in out here too.

https://www.aopa.org/news-and-media/all-news/2021/july/27/ga...

[lutorm]

I think at least all models of the Cirrus, one of the best selling general aviation planes right now, require 100 octane gas.

To be clear, none require leaded fuel, per se, but until this year there was no approved unleaded 100-octane fuel.