[ProfSienna]

Our 2022 Sienna averaged 37/38 MPG until about 7500 miles. We are now at 9500 and averaging 29/30 MPG under the same driving conditions. This has dropped off in the last 2000 miles and I am concerned.

I typically change my own synthetic oil at 5K intervals but Toyota would only cover on 10K intervals for their warranty/ToyotaCare service. Since it is new, I followed their recommendation. Besides oil breakdown, which would seem wild for this dropoff, any other thoughts?

[Apologies if this has been covered previously; I could not find anything on this specific issue but my forum search my have failed (if so, please link).]

 

[Jpl572103]

Low outside temps may be part of the problem. The engine needs to run more and maintain a certain temp so that the computers will all stay nice and toasty. But seriously I would not worry about it. It will bounce back. I have owned many cars,over 40 of them. My last car was a 2021 Sienna LE,before that a 2020 Chevy bolt, before that a 2014 Prius,before that a 2010 Prius V, etc.
Too many short errands or trips can also give you worse mileage it the outside temps are low. Your van's engine must maintain an acceptable temperature in order to utilize the EV side of the van. Batteries work better when warm.

 

[PetTaxi]

Also, winter blend gas will reduce MPG 10-15%

 

[ProfSienna]

Thanks @Jpl572103 @PetTaxi. Great thoughts. The sharp decline started in late august, early September. Temps were above 60 until a couple weeks ago and I think they started winter blend about a month ago. Is anyone else getting 29/30 MPG w high eco scores?

 

[PetTaxi]

Tire pressure? Carrying extra cargo? Holiday stress expressed in driving technique?

 

[Chubbysumo]

Thanks @Jpl572103 @PetTaxi. Great thoughts. The sharp decline started in late august, early September. Temps were above 60 until a couple weeks ago and I think they started winter blend about a month ago. Is anyone else getting 29/30 MPG w high eco scores?

yes, with winter cold, and snow tires, im getting between 25 and 35mpg.

 

[pamhar]

Our last fillup at end of Nov was about 39mpg in temps below 60f.

Keep monitoring in case cause is something other then what other posts mentioned.

Based on just CPU mpg we're at about 36mpg so far in December but CPU is optimistic so will update after next fillup with manual calculation.

 

[cougarhound]

yea mine dropped too. I was getting around 38mpg combined until the temperature dipped recently. I think idling also drops the mpg. We sit in the car with the heater on while waiting for kids to finish their activities. So gas is burning but you're not moving.

miles gallons dollars mpg ? 8.94 318.5 8.145 39.10374463 410.1 10.496 43.02 39.07202744 304.8 8.775 32.63 34.73504274 423.8 12.122 48.48 34.96122752 364.9 8.868 31.03 41.14794768 ? 9.027 388.9 11.404 41.04 34.10206945 374 12.148 43.72 30.78696082

 

[Sienna9816]

On top of what's been said already, check individual trip mileage if you don't already.

Turn off the child alert. Once done this, you will see trip mileage after you shut-off car, but before opening any doors. This way, you can see if particular trips and/or drivers are causing most of the low mileages.

FWIW, we get about 29-31 in summer, 25-27 in winter. When I let my friend drive it, he easily gets 38-40 in summer.

 

[cougarhound]

If it makes you feel better conventional gasoline engines lose about 12-15% in the winter too. EVs also lose range.

Fuel Economy in Cold Weather

Cold weather can reduce your fuel economy. Our tips can help improve your gas mileage when temperatures drop.

www.fueleconomy.gov

.

 

[20swrt]

I cannot stress this enough. Use your tpms display and make sure your tire pressure never drops below 35 psi.

 

[Velox003]

Snow Tires? They tend to reduce my mileage by a lot due to them not being low friction like the OEM tires.

 

[jseyfert3]

Winter gas may have slightly less energy, but most of the gas usage is warming up a cold engine, and primarily air density. Air drag is linearly proportional to air density. Going from 90 °F to 40 °F increases air density by 10%. On highway driving, something like 70% of the power to drive a vehicle may be used to overcome air drag, with the rest being rolling resistance of the tires and drivedrain losses. So even with the same gas, highway MPG from 90 to 40 °F will decrease by something like 7%. So if you can get 40 MPG highway driving at 90 °F, you'd expect a 5 MPG loss just due to the air density increase alone at 40 °F, all other factors being equal. And they aren't, as winter blends may have slightly less energy (not significantly so), and cold engines burn rich as they don't vaporize as much fuel as when they are warm, and lots of people idle engines to warm up their vehicles in the winter, which will further reduce MPG.

 

[slk]

Snow tires and winter blend gasoline will reduce your mileage. Throw in longer idling times as you wait for the windshield to defrost and you’ll be down at 39 mpg in no time.

 

[cougarhound]

Batteries don't like the cold. After watching this video I was amazed that most of these lithium battery jumpers failed after just freezing them at 32 degrees.

Sucks to be in Canada. Lol.

 

[curtlewis951]

Low outside temps may be part of the problem. The engine needs to run more and maintain a certain temp so that the computers will all stay nice and toasty. But seriously I would not worry about it. It will bounce back. I have owned many cars,over 40 of them. My last car was a 2021 Sienna LE,before that a 2020 Chevy bolt, before that a 2014 Prius,before that a 2010 Prius V, etc.
Too many short errands or trips can also give you worse mileage it the outside temps are low. Your van's engine must maintain an acceptable temperature in order to utilize the EV side of the van. Batteries work better when warm.

My 2022 Sienna has 1200 miles on it getting 35 mpg but I noticed when I turn car off on dash shows 48 mpg for a split second before it goes away would that be mpg for just that trip and the other one that I pull up on the steering wheel is an avg ?

 

[Sienna9816]

My 2022 Sienna has 1200 miles on it getting 35 mpg but I noticed when I turn car off on dash shows 48 mpg for a split second before it goes away would that be mpg for just that trip and the other one that I pull up on the steering wheel is an avg ?

Do you have "Rear child seat" reminder on? If you turn it off, you will see the Trip MPG after you shutoff the engine, but before you open any doors. You can also change MID MPG settings to pick 1 of 3 options. IIRC, they are trip/tank/since last reset or something like it.

 

[JasonFH]

I wish I could get anywhere near where you guys are getting. We haven't gotten a single tank over 32 mpg since we bought our '22 Platinum AWD. Right now our average according to Fuelly is 31 MPG. It's not the 36-38 we expected when we bought it. It now has 20k miles and has gone on many long road trips, lots of around town. Tried hypermiling it for many tanks with no change. I've always gotten above the estimated fuel mileage in all my vehicles, so I know it's not how I'm driving it.

 

[pamhar]

I wish I could get anywhere near where you guys are getting. We haven't gotten a single tank over 32 mpg since we bought our '22 Platinum AWD. Right now our average according to Fuelly is 31 MPG. It's not the 36-38 we expected when we bought it. It now has 20k miles and has gone on many long road trips, lots of around town. Tried hypermiling it for many tanks with no change. I've always gotten above the estimated fuel mileage in all my vehicles, so I know it's not how I'm driving it.

Checked PSI?
How aggressive on heat and using heated seats?

 

[JasonFH]

Checked PSI?
How aggressive on heat and using heated seats?

Tire pressure is 36PSI all around. Checked regularly.
The heater is generally set to around 68-70 in the winter and a bit warmer in the summer. Kids run theirs a bit hotter occasionally. Heated seats often in the winter, but no change really in summer vs winter MPG for us. Maybe 1 mpg.