Hybrid gas milage drop!!!

[hcforde]

After a couple of thousand miles of breaking in the XLT Hybrid I took a trip to Michigan from Texas and was getting an average of 35-36mpg going 65-80mph on the highway in both directions. On my return, I get an oil change(at the dealership) at about 5500 miles. I am now getting about 32-35 mpg in city driving.

When I brought it up to the service manager his thought was "summer gas", which makes no sense because the car is more efficient when warm my thought was wrong oil. I am using the same Sams Club gas even on the trip. Prior to the trip, the in-city MPG was averaging 40-42mpg. My driving habits have not changed and I have the same routine to the same stores and other places. I really do not see air conditioning dropping it down that much either.

Any insight as to the drop in MPG?

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[Cannedtunafishisgood]

Check your 12v battery voltage. You likely have the known bad harness...
The idea is there is not a good connection to the 12v battery so it doesn't get charged properly. This will in turn keep the engine running in an effort to get voltage from the high volt battery to the 12v.

 

[DeJay]

I may be wrong, but I believe your shop man is correct.
Summer blend gasoline contains alcohol to reduce pollution. We have summer blend here in Wisconsin and there is agreement that there is a drop in milage in summer due to the blend. We also lose milage in winter due to the cold even using unblended gas. You have can have a few less miles per gallon or climate change.

 

[LC48]

Could be both OP, summer blend and increased A/C use. The ethanol blend may drop your mileage 3-5% dependent upon how much denaturant is added to the alcohol. A/C use in general will cost you mileage, but this varies widely across vehicles. Have you noticed any difference in how often your ICE kicks in or how long?

 

[n0maverick]

AC is killer on hybrid. Since it only runs from battery the battery level doesn't get/stay high enough to do much powering the wheels. Hybrids are amazing 50-70 degrees, 40-50mph, flat ground, and some stops.

 

[MakinDoForNow]

After a couple of thousand miles of breaking in the XLT Hybrid I took a trip to Michigan from Texas and was getting an average of 35-36mpg going 65-80mph on the highway in both directions. On my return, I get an oil change(at the dealership) at about 5500 miles. I am now getting about 32-35 mpg in city driving.

When I brought it up to the service manager his thought was "summer gas", which makes no sense because the car is more efficient when warm my thought was wrong oil. I am using the same Sams Club gas even on the trip. Prior to the trip, the in-city MPG was averaging 40-42mpg. My driving habits have not changed and I have the same routine to the same stores and other places. I really do not see air conditioning dropping it down that much either.

Any insight as to the drop in MPG?

Number one suspect is heat and alcohol in gas. Next full fill-up find a pure gas pump and try that. I would probably try 89 or higher octane on full tank with the Sam's gas. I am in Austin do not drive enough to tell on mine. I believe that the transaxle fluid which is cooled/heated by the radiator fluid which has a heat exchanger and if needed can use the electric AC condenser to assist cooling the transaxle fluid IF NEEDED. It is very important to keep the stators of the drive motor and the generator/starter motor below a certain temp. The AC may be running much more than you think it is! Might take a test drive before 9-10am to compare mpg's??? Also while they had your oil change happening did they also do a software update of any kind? Probably not since you were most likely waiting in lobby. With gasoline getting in shorter supply it may be that the alcohol may be 10-12% instead of 8-10%. I do not know what % parameters they have to mix to. I would, however expect higher octane gas to have a positive effect and maybe a lower % of Alcohol. I do not know but an idea to think about.

 

[hcforde]

OK, but can summer gas and air conditioning account for a 20% drop in mpg? That seems a bit high to me.

 

[LC48]

I wouldn't expect the fuel to account for that no sir. I hate ethanol blends with a passion, but a drop more than 5% at the outside is not normal for an E10 blend even with minimal denaturant.

Air conditioning, especially with the current Tejas heat, will certainly hit you in mpg, the hybrid guys may be able to give us some more insight on that, @n0maverick above believes it is tuff on hybrid batteries leaving less capacity for the drive motor(s).

How accurate have you found the installed mpg meter to be compared to hand calculated? If it is pretty close some short runs in cooler overnight temps might provide a good clue or two. If your installed meter is off like many are there are threads on here to get into engineering mode and adjust the offset - mine now stays within +/- .3 mpg.

Tire pressures? Does anything else seem "off" recently with the truck?
Bill

 

[skinnyboy]

Number one suspect is heat and alcohol in gas. Next full fill-up find a pure gas pump and try that. I would probably try 89 or higher octane on full tank with the Sam's gas. I am in Austin do not drive enough to tell on mine. I believe that the transaxle fluid which is cooled/heated by the radiator fluid which has a heat exchanger and if needed can use the electric AC condenser to assist cooling the transaxle fluid IF NEEDED. It is very important to keep the stators of the drive motor and the generator/starter motor below a certain temp. The AC may be running much more than you think it is! Might take a test drive before 9-10am to compare mpg's??? Also while they had your oil change happening did they also do a software update of any kind? Probably not since you were most likely waiting in lobby. With gasoline getting in shorter supply it may be that the alcohol may be 10-12% instead of 8-10%. I do not know what % parameters they have to mix to. I would, however expect higher octane gas to have a positive effect and maybe a lower % of Alcohol. I do not know but an idea to think about.

The transaxle in my Prius has no heating or cooling, and the design is very similar to the Ford. Where did the information regarding outside temp control of the transaxle come from?

Cheers.

 

[MakinDoForNow]

The transaxle in my Prius has no heating or cooling, and the design is very similar to the Ford. Where did the information regarding outside temp control of the transaxle come from?

Cheers.

I will look for link. I suspect that in use the drive motor will mainly heat the fluid.

 

[hcforde]

Number one suspect is heat and alcohol in gas. Next full fill-up find a pure gas pump and try that. I would probably try 89 or higher octane on full tank with the Sam's gas. I am in Austin do not drive enough to tell on mine. I believe that the transaxle fluid which is cooled/heated by the radiator fluid which has a heat exchanger and if needed can use the electric AC condenser to assist cooling the transaxle fluid IF NEEDED. It is very important to keep the stators of the drive motor and the generator/starter motor below a certain temp. The AC may be running much more than you think it is! Might take a test drive before 9-10am to compare mpg's??? Also while they had your oil change happening did they also do a software update of any kind? Probably not since you were most likely waiting in lobby. With gasoline getting in shorter supply it may be that the alcohol may be 10-12% instead of 8-10%. I do not know what % parameters they have to mix to. I would, however expect higher octane gas to have a positive effect and maybe a lower % of Alcohol. I do not know but an idea to think about.

Hey, I am in Austin also; the 183 & McNeil area.

I have been considering getting some pure gas. They have it at the Murphy's station on 620/183 in the Lakeline area.

 

[projectvortex]

Interesting article on summer vs winter blend gas.

https://aaaliving.acg.aaa.com/auto/what-to-know-about-gasoline-blends-summer-vs-winter/

 

[Dan]

Same problem here I use the AC a lot as we have been in the hundreds or high nineties for a couple weeks now, I went from regular (87) to mid grade (89) when the weather got hot and saw some improvement then I recently went to premium (91) and get amazing gas mileage. I was averaging 20-22 on my route home (all up hill) using regular, now I average 28-32 using premium.

 

[icegradner]

I may be wrong, but I believe your shop man is correct.
Summer blend gasoline contains alcohol to reduce pollution. We have summer blend here in Wisconsin and there is agreement that there is a drop in milage in summer due to the blend. We also lose milage in winter due to the cold even using unblended gas. You have can have a few less miles per gallon or climate change.

Maybe, but generally speaking summer gas is more efficient than winter gas, not worse. Winter gas has anti-freezing additives in regions were it gets cold, which causes a drop in efficiency. Gas in our region has 10% ethanol all year round, efficiency is noticeably better in summer, 2-5MPG on average over winter gas.

Heavy use of the HVAC system is the likely reason for drop in fuel economy. To improve efficeancy use the air recycle feature, once the air the the vehicle is at the set temperature it won't have to work as hard. Cycle in fresh air every 20-30 minutes or so and you'll be fine and save gas.

 

[Vols44]

Same problem here I use the AC a lot as we have been in the hundreds or high nineties for a couple weeks now, I went from regular (87) to mid grade (89) when the weather got hot and saw some improvement then I recently went to premium (91) and get amazing gas mileage. I was averaging 20-22 on my route home (all up hill) using regular, now I average 28-32 using premium.

I'd like to use an online calculator to see if the .30 cents per gallon price difference in 91 versus 87 octane is worth the investment if I can improve my gas mileage significantly. I probably wait til the engine is past it's broken in period before conducting the octane experiment. I do know ethanol burns faster than gasoline and most 87 and 89 octane contains 10% milled corn.

Wikipedia says 25% of corn crops are designated for distilling. The price or corn rose 20% since the Russia-Ukraine conflict began. In my area the price of gas actually went down 5 cents in the last week.

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