How much does an uphill eat into MPG? My morning commute is a gradual downhill which is fantastic, but going back home means I'm steadily going uphill. I think I roughly lose 20-25%, and nothing seems to make it get that much better, outside of getting an even better downhill run and raising trip avg that way. I can't tell the difference between PnG or just holding steady, at best it's like going from 52 to 54. The average speed is like, 20 - 40 mph for the steepest segment, which really sucks, can't get any momentum going.
My non-hybrid 2013 automatic Hyundai Elantra or our non-hybrid 2016 manual Elantra can get 45+MPG on level non-trafficked roads when I take it easy, while near sea level. Once I start ascending to a 4000foot mountain pass, the accumulated MPG drops to 30MG, maybe a trace lower if traffic gets me out of my careful driving. So I assume my spot MPG on the steepest slopes must be in the teens & probably not high teens. However once I am descending, hoping I don't have to get on the friction brakes or braking by compression too badly, I sometimes recover quite a bit of my MPG. If I am lucky I can get back to an accumulated 40-42MPG. The manual Elantra will get better MPG than the automatic while in the mountains.
Maybe check out some of Wayne's drives where he logs everything and routinely crosses mountain ranges.
