> I drive a 1st generation Honda Insight
1st gen Honda insight is "1999–2006" (1) so this anecdote is dated. Manuals were more efficient, but currently no, they are not so any more.
Apparently that only changed recently, shortly after this time period (2)
1) https://en.wikipedia.org/wiki/Honda_Insight
2)
https://www.energy.gov/eere/vehicles/articles/fotw-1127-marc...
https://www.greencarguide.co.uk/blog/automatic-vs-manual-car...
https://www.car.co.uk/media/blogs/fuel-alternative-fuels/do-...
https://www.reddit.com/r/cars/comments/9kye2h/comment/e72qx6...