I have a 2020 p500 and ride mostly dirt roads. I like to run around 10 to 15 mph and usually 4th gear. Is lugging at lower rpms ok on clutch. I'm not talking valve rattling lug just lower rpms.I also run 27 inch tires.
Lugging is never good, but if you are on the flat just mostly coasting along it will be fine, start up a grade you will know right away if you experience lug then shift. Unresponsive throttle tells you a lot.
I try to keep the rpms in in the middle of the range on trails. If it downshifts under load, I consider it my bad. But on flats just cruising, a little less rpms. But like said by others, the computer should let you know.
Better yet, my wife and I put some miles on a 2015 p500.
She would slow down and lug it to the point it would stall.
If I said anything it wouldn't go well (could have been my choice of words).
If I didn't let her drive it went even worse.
I love the auto down shift on our 2018.
Honda added a feature I needed and I didn't even know I needed that feature.
Mine is a 2018 and it shifts own it's own even though I feel sometimes the speed and rpm's don't jive. Also when in auto, I can still use the paddle shifters if I feel my rpm's are too high or low. Not sure if that is normal, but I like it. For the most part I think it does great, never falls on it's face or just redlines the engine.