[Smilo1975]

My gas mileage in my 2017 Hybrid has gone from 37 mpg to 24 mpg all of a sudden. I took it into the dealer and they blame bad gas but I'm not believing that one. I have bought gas from 3 different stations since this issue has happened and nothing changes. I also have read that the cold winter temps could be the issue or running the heater. But, I didn't have this issue the past 2 winter's that I have had the car. Tire pressure is good... does anyone have any other suggestions of what it could be?

 

[Turbonut]

A drop in fuel mileage is always a challenge, but normally it is what you see.
Don't know mileage on the car, but check brakes for dragging as one might be hotter than the others.
Is there anything on the dash to indicate the % of time the car is in battery power compared to gas?
If so, is it about the same as what has been in the past?
Fill it up and take the car on 10-15 higuway mile trip and check the mileage.

 

[Smilo1975]

My car has 21k miles. I'm not sure if there is anything about the time in battery compared to gas, but I will absolutely check.

I will try filling it up and going on the highway. I only work 4 miles away from home so I don't do much highway driving. Maybe that will help. Thank you and I'll keep you posted!

 

[vamdemon]

It's usually not because of the gas. Many US gas stations have top tier gas. You can top up gas and add fuel additives like Gumout and check on the next tank.

I don't know which area you live but the gas mileage can go really bad in cold winters. The heater and the battery efficiency drops a lot. However, I was watching a youtube channel TheTopher before I bought my 17 hybrid and he still got around 29 MPG in his winter test drive week. My worst gas mileage in Seattle area was 3 weeks ago when it snowed badly and my commute is all local and I can still get around 27MPG.

I would first inspect carbon deposit/regen braking.

 

[Therosses5]

Another factor is tires. Did you happen to replace tires not used in past winters? We lost 10mpg when we replaced the oem tires that were starting to go bald after 20k. We lose another 5mpg due to the cold here in Coeur D alene, ID.