Break-in Gas Mileage

[RC57]

2024 Limited 4WD I bought in June. Used mainly to get groceries until this weekend when I made my first road trip. Round trip from Jacksonville FL to Raleigh NC. Traffic was free flowing the whole trip. Used the cruise control to go 74mph both ways. Weather was good with no more than a light breeze. About 500 miles each way. Got a steady 18.1 mi/gal on the way there. 20.1 on the way back. Fuel mileage went up when the odometer hit ~3000 miles as I approached Raleigh. It was like throwing a switch.

Does Toyota run the truck rich for the first 3k miles?

 

[Bmnorm2]

It has more to do with the piston rings wearing to fit the cylinders.. There is excess friction until they wear to fit. Around 3k-5k is the typical break in mileage. There are other sources of excess friction like the differential gear mesh that will wear to fit as well.

Comparing two different directions of travel also isn’t great because mileage can be affected by elevation gain or loss and wind direction. Best to compare the same route in same direction.

 

[RC57]

No appreciable wind or elevation change either way. There's no way the rings after 3K miles suddenly bedded in. The mileage change occurred over a very short distance. A step-wise change vs gradual doesn't fit with a mechanical break-in.

It has more to do with the piston rings wearing to fit the cylinders.. There is excess friction until they wear to fit. Around 3k-5k is the typical break in mileage. There are other sources of excess friction like the differential gear mesh that will wear to fit as well.

Comparing two different directions of travel also isn’t great because mileage can be affected by elevation gain or loss and wind direction. Best to compare the same route in same direction.

 

[Hungryhawk]

The dashboard readout averages mileage.
From actual gallons consumed from fill-up to fill-up and miles driven between those gas ups you can calculate a better MPG. The inaccuracy will be the gas station pump cut off when full setting.
If possible use same fuel pump and same gas station.
The more fill-ups and more miles driven, the better accuracy. Compare these MPG to the dashboard readouts. Then you will know, in the future, how accurate the dashboard readout numbers are.

 

[RC57]

The dashboard readout averages mileage.
From actual gallons consumed from fill-up to fill-up and miles driven between those gas ups you can calculate a better MPG. The inaccuracy will be the gas station pump cut off when full setting.
If possible use same fuel pump and same gas station.
The more fill-ups and more miles driven, the better accuracy. Compare these MPG to the dashboard readouts. Then you will know, in the future, how accurate the dashboard readout numbers are.

The dashboard readout isn't based on the tank, it's based on the fuel injection time. There is no inaccuracy in the dash readout due to gas station fuel nozzle shutoff variability. That variability won'teffect trip meter calculations either. Both numbers have been in close agreement.

18mpg steady over multiple tank top offs for 450 miles at ~74mph. As I approached Raleigh the average started creeping up. Then it was 20mpg steady over multiple tank top offs for another 500 miles at ~74mph. I95 along the coast with free flowing traffic the whole time. Didn't spend any time drafting semis.

 

[RC57]

My theory is the engineers run the engine slightly rich during break-in to lower combustion chamber temperatures. That would provide some relief to the new rings during break-in when friction is higher.

 

[CutthroatSlam]

No appreciable wind or elevation change either way. There's no way the rings after 3K miles suddenly bedded in. The mileage change occurred over a very short distance. A step-wise change vs gradual doesn't fit with a mechanical break-in.

No, he’s actually spot on with the miles needed to fully seat the rings and even moreso with measuring over the same route in the same direction. Wind has an affect on mileage. Also, get used to variability in that dash mileage calculator. I’ve seen it range from 14.5 mpg to 20.5 mpg. Most of the time it’s in the 18.5 to 19.5 range.

 

[Ripper238]

I have always experience my vehicles running better after a long trip, even better MPG in some cases. Everything is well lubed and worked out. Especially on a new vehicle.

The other factor is your miles back were likely all better MPG miles vs whatever driving you did leading up to the trip.

 

[Bmnorm2]

My theory is the engineers run the engine slightly rich during break-in to lower combustion chamber temperatures. That would provide some relief to the new rings during break-in when friction is higher.

No. I spent 5 years as an engineer for engines. Including controls and tuning.

You asked for an answer and you got the correct one. If you didn't want an answer and just wanted someone to tell you your theory was correct then why post? A drive from NC to FL isn't a time interval that would compare to "like a switch". Toyota already runs these engines fairly rich while under load to be conversative.

 

[Saker]

No. I spent 5 years as an engineer for engines. Including controls and tuning.

You asked for an answer and you got the correct one. If you didn't want an answer and just wanted someone to tell you your theory was correct then why post? A drive from NC to FL isn't a time interval that would compare to "like a switch". Toyota already runs these engines fairly rich while under load to be conversative.

Agree with this.
Remember also the ECU is constantly looking and adjusting until it learns your driving.

Way too many factors to consider.

 

[RC57]

No. I spent 5 years as an engineer for engines. Including controls and tuning.

You asked for an answer and you got the correct one. If you didn't want an answer and just wanted someone to tell you your theory was correct then why post? A drive from NC to FL isn't a time interval that would compare to "like a switch". Toyota already runs these engines fairly rich while under load to be conversative.

Thanks for that input. When I say like a switch, 450 miles of 18mpg, then in short order, 500 miles of 20mpg. If that is due to rings bedding in, when they didn't do it for 3000 miles, so be it. Conditions in both cases were as close as can be expected ever in the real world.

 

[Bmnorm2]

Thanks for that input. When I say like a switch, 450 miles of 18mpg, then in short order, 500 miles of 20mpg. If that is due to rings bedding in, when they didn't do it for 3000 miles, so be it. Conditions in both cases were as close as can be expected ever in the real world.

Most likely due to the different direction and all the variables at play with that. Even over shorter drives that don’t have large elevation changes or traffic differences I may get 22 mpg on the way there and 24 mpg on the way back driving in the same manner.

I manually track my fuel economy as well as very carefully watch the computer. Surprisingly, the computer is extremely accurate if you drive consistently. The computer has been within +/- 0.3 mpg for me over 55k miles.

Since I own proper sports cars I drive the 4Runner as efficiently as possible and have managed 19.8 mpg over 55k miles. It’s a game for me and I don’t find driving the 4Runner hard to be rewarding.

I recommend manually tracking your mpg. I noticed a discernible difference around 5k miles once the rings were fully bedded. I also spent time when the engine was brand new doing break-in procedures.

 

[RC57]

I've been tracking my fuel mileage every tank for the last 50 years, starting when there was gas rationing in the 70s.

I've driven this same route many dozens of times in my 99 4Runner, and almost always got ~20mpg both ways. _Strong_ headwinds, and stop and go traffic would drop it below 19.

I'm pleased that the new one is now getting 20mpg. When I saw it was only getting 18mpg, I was disappointed. I was expecting 20. I'll reiterate again, there were no external environmental factors effecting mileage. I95 on the coast is flat, great traffic, and there was no appreciable wind.

Most likely due to the different direction and all the variables at play with that. Even over shorter drives that don’t have large elevation changes or traffic differences I may get 22 mpg on the way there and 24 mpg on the way back driving in the same manner.

I manually track my fuel economy as well as very carefully watch the computer. Surprisingly, the computer is extremely accurate if you drive consistently. The computer has been within +/- 0.3 mpg for me over 55k miles.

Since I own proper sports cars I drive the 4Runner as efficiently as possible and have managed 19.8 mpg over 55k miles. It’s a game for me and I don’t find driving the 4Runner hard to be rewarding.

I recommend manually tracking your mpg. I noticed a discernible difference around 5k miles once the rings were fully bedded. I also spent time when the engine was brand new doing break-in procedures.

 

[thennen]

Someone, please correct me if I'm wrong here. But I believe the vehicle leaves the factory with a default transmission profile. As the owner drives, the vehicle learns his driving style to some extent, and tweaks shift patterns and timings accordingly. So it could be that some decisions were made by the vehicle ~3000 miles, maybe unnoticed by the driver. Just a thought.

I do know that, after I had the transmission fluid replaced in my 2019 a couple years ago, the shift pattern definitely had changed. It has worked its way back to 'normal' since then.

 

[RC57]

Truck was in 5th gear the whole time, except a few minutes going over the Dames Point Bridge. I95 is flat and straight.

Someone, please correct me if I'm wrong here. But I believe the vehicle leaves the factory with a default transmission profile. As the owner drives, the vehicle learns his driving style to some extent, and tweaks shift patterns and timings accordingly. So it could be that some decisions were made by the vehicle ~3000 miles, maybe unnoticed by the driver. Just a thought.

I do know that, after I had the transmission fluid replaced in my 2019 a couple years ago, the shift pattern definitely had changed. It has worked its way back to 'normal' since then.

 

[CutthroatSlam]

Drove the 2023 ORP w/ 47K miles from Stevensville, Montana to Fullerton, CA over the weekend. Highest was 21.5 mpg. From North Las Vargas to Fullerton the average was 20.7. There are several large grades on that section. Fortunately no wind.

 

[trainman605]

I don't know what your driving conditions, or ways are, but I can tell you I drive my new 2024 4 Runner only around 5,000 miles per year. Now when I have driven on a few road trips I have been able to get 22-23 mpg on the open road and driving around 65 mph. If I drive 70-75 mph the mileage drops down quite a bit, now I will say here at 79 and I personally like the 65-mph speed which I realize wouldn't work for many of you. All being said, I didn't buy the 4 Runner for fuel mileage, I purchased the 4 Runner because I just wanted one and I'm very happy with it. If you purchased a 4 Runner and expect more fuel mileage you probably didn't do your homework before your purchase.

 

[CutthroatSlam]

From North Las Vegas to Fullerton the speed limit is mostly 70 mph, though most are going 80+ mph. Did have a truck fire off to the side of the first large grade which resulted in a 4 mile back up to a crawl.

 

[RC57]

If you purchased a 4 Runner and expect more fuel mileage you probably didn't do your homework before your purchase.

I did my homework. Sticker lists highway at 19, and under ideal conditions that's what I expect. I figured it only got 19 due to full-time 4WD. Also homework-wise, I bought the Limited for the lockable torsen center diff. It's useful when on dry pavement with icy patches when I visit NC in the winter. Don't know what mpg the sticker says for the part-time 4WD. No rock crawling here. If you want to do serious off-road in Florida, you set up more like a swamp buggy. Not something I want to spend time with on the super-slab.