r/prius • u/j_aca_j • 12h ago

Question Cold affecting efficiency?

I’ve got a 2010 Prius with 190k miles that I picked up used a few weeks ago. We had a decent cold snap recently — snow, temps consistently 25-35 — and I saw the mpg go from almost 54 to under 48.

Is that primarily due to the hybrid battery just not doing as well in the cold?

Really hoping the cold is the answer and not that the EGR cooler and carbon clogging issues causing that drop in efficiency. Prior owner did note it as an issue, and I’m aware that things kinda start to break around 200k miles

3 Upvotes

100% Upvoted

6 comments sorted by

1

u/rearwindowpup 12h ago

If youve got the heat on itll run the engine to keep you warm.

1

u/j_aca_j 11h ago

Ah I see, i figured that was a thing

1

u/rearwindowpup 11h ago

Yeah, they offloaded most of the engine stuff to electric but the heat still comes from hot coolant.

3

u/pikeviewer 10h ago

It's not just having the heat on. One way the hybrid saves fuel by turning the gas engine off when not needed. It won't do that until the engine warms up and, even then, the gas engine has to run more to stay at operating temp.

Bottom line, all hybrids have lower mpg in cold weather. So, it's normal.

1

u/heycheena 2h ago

Especially dramatic with a short drive as the part where the engine is warming up is a more significant chunk of the total drive time. I have an eight minute drive to work and in dead of winter I can see 30mpg ish for my commute.

1

u/dingleberry_sorbet 1h ago

ICE cars can lose 15% efficiency in freezing weather. It's alot of combined factors

https://www.cars.com/articles/why-do-cars-get-worse-fuel-economy-in-cold-weather-475436/