2020 Toyota Tacoma TRD off road Hiway Gas Mileage issues?

I joined this forum because of this specific issue. I have a 2020 TRD offroad 4x4. Around town it gets fair mileage. But take it on the freeway, the mileage Tanks big time. Im getting 14.9-16.5. Empty, towing nothing. The toyota dealer says thats the way it is. Never had i had any vehicle get worse mileage on the freeway than city driving. Is this a transmission programming issue (Yes even though the dealer said they fixed the goofy shifting, this thing will stay in lower gear way too long, and I have to manually upshift at times)? Any others with similar experiences/trouble shooting advice?
I drove almost 2k miles in the first 1 1/2 months. Recorded the actual gas I put in, verse rely on the computer reading. I even drove 10 miles per hour lower than posted speed limit through one stretch, same mpg. There was no idling to warm up or any of that stuff.

 

Need more details. Is your truck stock?

14-16 range seems low for hwy. Even my 2nd gen hitting 75mph hwy I was getting 18-19, only modification being 265/75/16 tires.

What’s your highway speed and typical distance?

 

This is brand new off the lot, no mods at all. V6. Took long road trip over Christmas, almost 2k round trip. 95 percent freeway. 80 miles is the posted limit for part of it, 75 for the other parts and 65 in CA/LA area. I took it into the dealer before this trip expressing my concerns (less than 500 miles on it), driving about 40 miles (each way) and back, to the next big town from ours and back, it was only getting 15 mpg.

 

My 2019 off road, stock, sounds similar to your situation. When I go 65-75 mph, the best I get is around 16-17 mpg. I can get around 20 mpg if I am going a steady 40-55 mph. I am not sure how much affect winter blend gas has on this. I can't wait to gt my D or E rated tires @ 50 lbs each to see what happens to my gas mileage!

 

I can understand a 10 percent variance due to blends etc, but they (toyota) claims it should get 23 mpg. Our experience is well over 20 percent less than that. This is our 3rd Toyota product, and for the most part we have been very happy with them and the mpg, not this Truck unfortunately. And the way we have gotten seemingly total run around by toyota. Telling us, well there are no error codes. Lame to say the least. If our experience is normal for this vehicle that is one thing, if not that's another, which we are trying to sort out. thank you.

 

Do you have a bed cover?
Those reduce MPGs by 2-4 depending if it's a heavy fiberglass top but tops screw with the aerodynamics and LOWER MPG (contrary to what people think about them).

Also vehicles get lower mileage the faster they drive. For my 2013 60-65mph seems to be the threshold. If I'm driving 70-75+ then my mpg drop to about 16.

It also comes down to how you drive as well and terrain and wind.

 

Thank you for the input and your experience. I didn't have a topper at the time, I do now. One point I should have mentioned earlier, after driving for several hours, stopping for gas and continuing for another couple of hours. All of a sudden I was getting 22-25 mph, once we stopped for the night and started the next day, the mileage went back down to the 15-16 range. This happened twice. Two very different locations, one in UTAH high elevation and the other in SO Call, low elevation. Seems very odd to me and it seems to show this vehicle is capable of decent hiway mileage. I don't know if it is staying in the wrong gears, the SW is off, or there is some kind of sensor that isnt installed/working the way it should. Before buying this truck i reviewed others experience where others said they were getting in the low 20s one hiways. So it seems it is supposed to get in the hi teens/low twenties. We are just not seeing it and trying to understand why. I dont want to monkey with an aftermarket reprogramming while its under warranty, but if anyone has good experience with one please let me know. thank you.

 

It sounds to me like something is wrong. Has Toyota said anything? I would be tempted to log some obd data and see if anything was suspicious. Could be a bad sensor or something.

 

Have you logged the MPG by hand the old fashioned way (miles/gallons put in tank) and compared it to what the truck is saying?

 

Yes, I am a bit old fashion that way. But the on-board mileage gauge seems fairly consistent with what the manual calculations. Maybe I bought from a bad dealer, they don't want to do anything, they told me, if nothing is "broken" they dont get reimbursed from Toyota. They said no "error codes" so nothing is wrong, instead handed me a packet on mileage variations/how they are determined driver/conditions is the problem. Thanks, like i just graduated HS.. I have had over 15 vehicles almost 45 years driving and I think I have learned a bit about driving and MPG by now. I just don't know these newer vehicles how they operate to know if its hardware, SW, or just the way these Trucks are. The dealer just says, you haven't driven anything like this before, they don't drive like any other vehicle. Sorry, for almost 50k, I wont accept that off the top. Appreciate any advice, or if anyone has had similar issues/experience.

 

Could your good/bad mileage correlated to speed?

I've got 1600 miles on mine. I have noticed that the truck really likes 45-55 mph. If I drive routes without much stop & go, and the top speed is 55 or less, the mileage for that trip can be around 24. I've seen almost 25mpg on a 10 mile trip at 45-55. When I get on the interstate at 75, the mileage drops a lot. Going to church (25 minutes, 40% at 40mph and 60% at 75mph) the mileage is 16-17. If I drove 80, I wouldn't be surprised by 14-16mpg.

I remember in highschool physics they said we can ignore wind resistance in calculations below 50mph. Once you cross 50, the wind resistance really starts to add up.

Also, on cross country trips, keep an eye out for elevation changes. That throw the mileage up or down.

 

Thanks KsJoe. This seems like our experience, the truck is great around down, gets respectable mileage, but once you hit the open road, it tanks. To me this seems very abnormal behavior. for a small/mid size truck. One would expect it to get at least city mileage, but not go well below that. Had I known that, I would have sprung for a full size pickup, why pay all that gas expense to be cramped in a small uncomfortable cabin with the family and pets on long trips. Piece of garbage if this is what Toyota is putting out on the market today. I have a hard time believing this is how it is supposed to operate. I still think there is an issue with the transmission or how it shifts or decides what gears to be in. Just a hunch, Using that button to keep it in gear longer seems even worse than leaving it off.

 

Bob, your experience matches my own, and I would be surprised if your vehicle is malfunctioning from the way it was designed. I am at 20k on the odometer on a still essentially stock vehicle (have only added a bit of armor weight) and have spent a fair amount of time paying attention to the Eco app on road trips and I think I can help you out with some of the confusion. So here goes:

1. The EPA system for measuring mileage doesn't account for wind, additional payload, A/C operation or elevation changes, and it appears to be heavily biased to speeds 55 mph or lower.
2. The wind dam on the front, that is not present on the Offroad model, is probably good for at least 1 mpg and is likely factored into the EPA estimate.
3. The mileage is very poor until the engine warms up. It appears that once temps get below about 40F, the first 5 minutes of operation has an average mileage of 8 to 10 mpg. If you are not driving for more than an hour, that first 5 minutes really pulls down the trip average. That's probably part of the reason why you see a increase in mileage in the middle of the trip after making a stop, as the new trip starts with a fully warmed engine.
4. Given Item 3 above, on the same tank of gas, if the ambient temp is 70F one day, and 30F the next (quite common in spring/fall in my parts), the average trip mileage for the same trip can vary by 5 to 6 mpg. Another example: when below freezing, a 5 mile trip in town is usually around 15 mpg. During the summer, that same exact trip is usually around 20 mpg.
5. I also get much better mileage in town, than on the road when driving above 60 mph, especially in the summer when the engine warms up quickly. The engine is most efficient when it is operating in the Atkinson cycle, which only happens when the engine is not under load. For this reason, I think its possible that I get better mileage with relatively quick accelerations from stops, as it allows me to feather the throttle for a longer duration by quickly getting up to speed. Mileage on flat ground will also be better than in rolling hills.
6. Wind. This is huge factor in mileage, especially once you get above 60 mph. I have a radar weather app (MyRadar) on my phone that shows the direction and relative speed of the wind graphically on a map. Depending on the wind direction and speed, mileage can swing 12 mpg on the interstate (15 mph steady tail vs head wind). Tail a semi truck with the Adaptive CC for a bit and notice how the Eco app bars change pretty significantly in height. It seems I am always driving into the wind for road trips, so my mileage is always pathetic. One of these days, I want to take a road trip where I just go where the wind takes me.
7. A/C will drop mileage about 2 to 3 mpg when on.
8. Payload weight also plays a roll, but is not as significant as you would expect if you are not towing, as once you are up to speed, the Atkinson cycle kicks in and all is good. If you are doing a lot of start/stop though, it matters more.
9. Toyota trucks have always gotten miserable mileage compared to their competition, because drive-train reliability has a measurable mpg cost. Turbos and transmissions with more gears will always get better mileage, but they will also wear out faster. It is no secret that the standard F150 package with an Ecoboost engine will get as good if not better mileage than the Tacoma, but those turbos and 10 speed transmissions won't run without problems nearly as long. That said, most people don't own a vehicle longer than 3 to 8 years, so the only real advantage in long-term reliability is resell.
10. Engines making relatively low torque are not going to be as efficient as engines with more torque when the engine is under load. As such, compact/midsize trucks have always been disappointing when it comes to mileage returns in the real world.

 

Thank you Pinem56. This is such a great forum and very much appreciate the feedback and expertise. I certainly agree with all your points, and perhaps I didn't frame my issues well enough. I certainly know about a lot of those points, but has anyone had issues with the transmission staying in lower gears, which drive up RPMs. Or other SW/Mechanical issues that they found, or learned about, causing lower than normal MPG? And any suggested fixes/work around to try to boost MPG. I am a test engineer by training, so I have some clue about leveling out variables etc, that's why I am very perplexed that it will get such poor mileage on the freeway starting out, but after being on the road for a few hours stopping and continuing, it will get very good mileage 23+, Same/Similar driving conditions. There is something wrong with this picture.

Driving this thing on the freeway is a real chore, and horrible user experience. I have video and need to figure out how to post, maybe I need to do a youtube on it. I thought this was a top rated truck with great resale, I really dont understand this at all, my 98 Ranger, was a much better all around vehicle, similar set up 20+ freeway mpg. (yes cheap cab materials) than this supposedly advance vehicle I traded up to. If all Tacomas are like this, Toyota has some serious issues and we wont ever consider another one. Thank you again for the great insights

 

I have encountered the delayed upshifting issue as well. My hypothesis on this is that it is due to ECU "learning". I have noticed that if the rolling hills are a consistent repeating of up then down, the upshifting will happen sooner after cresting each hill, than if the ups and downs are irregular, where you might go up, flatten off slightly, and then up again. In the later condition, the first time the ECU gets tricked into upshifting too soon, it will be more hesitant to upshift the second time coming up to the top of a hill. I would guess this is due AI programming to minimze shifting. I have had some success with going to S6 mode, to instigate quicker upshifts, but only marginally. In really curvy, hilly areas sometimes I'll go to S5 mode to reduce the amount of shifting.

Using 91 octane can also help a little bit with this, as the fuel trim adjustment for the higher octane will give you a bit more torque.

About the only real way to deal with this is an OV tune.

 

Yeah, sounds pretty standard. These trucks were rated at ~55mph to achieve stated MPG ratings, that’s why they’ll shift into 6th by 35mph if you let it. 70+ and mileage goes to shit, 80+ and forget about it. Over 131k miles on my 2016 I think the lifetime average was around 15.6. That’s probably 100k of 70+mph miles.

 

I just thought I would share some of my numbers although I have modifications.

2020 TRD Off Road 6 Speed Manual.
Method MR701 Wheels 17/8.5
Falken Wildpeaks A/T3W 265/70/17.
Leer XR100.
Prinsu Cab and Top Rack.

14.8 MPG highway, which is about 270 miles for a full tank. Speeds were 65-75mph the whole trip. The truck computer is no longer accurate so I ran the numbers myself.

I knew I was going to take a hit with the mods but didn't think it would be this much.

 

If I may speak from a mechanics point of view, assuming the truck is all OEM, unless your engine is malfunctioning/misfiring (flashing check engine light) or you have brakes dragging, there is literally nothing that can be done for MPG from a shops point of view. I get the few complaints from Volvo customers about not getting their "stickered mpg" and in reality, that sticker is mostly make believe as it requires the perfect world conditions which do not exist.

 

I get what I think is fair to great mileage, if I stay off the freeway. As soon as I go on the freeway, try to stay in cruise control I get flaky results, see picts, same mileage on the tank, flat road, same speed. totally different mileage. I get about 18.5 mpg around town, I make a trip to another town now, around 35 miles away at 80 mph freeway, the mileage drops to the 16 range. Is this normal, one would get worse mileage on the Freeway, than around town with a stock truck? Sometimes, it will jump, other times go well below. The shifting is nuts too, but I try to compensate with the manual shifter, drop it then put back to drive. This will knock it out of the lower gear.

 

I also want to chime in about less than satisfactory highway mpg. My 2020 OR SWB 4x4 had about 500 miles on it last weekend. Took it on its first long trip, anxious to see the MPG. Honestly expected > 20 as I use cruise and am usually light on the pedal.

Boy was I wrong. Divided the trip up into quadrants that consisted of small to large changes in elevation. Other variables were similar. Best I could get is ~18 mpg. Initially chalked it up the heavy Duratecs that came on the truck, break in period, etc... While they may certainly be factors, I have to primarily fault the transmission. It's just weird. I've never driven a car or truck w/an automatic transmission that genuinely felt like it didn't know what to do on the highway. Going up long hills it would shift from 6th, to 5th, to 6th, to 5th, etc... It actually cycled. Sure, I understand why some would do this, but it could have stayed in 6th. RPM's were fine. I shifted it from D to S then back to D (D2S2D) quickly and it would immediately shift from 5th to 6th. If I left it in D, the cycle would start again. Not aware of a satisfactory resolution to this issue. (If anyone who reads this travels Fancy Gap mountain on Interstate 77, I'm anxious to hear if their Tacoma exhibits the same behavior.)

Also, most of the time it would downshift to 5th on smaller inclines and after cresting them, stay in 5th (even on the decline). RPM's would be around 3k. I had to do the D2S2D quick shift to get it into 6th. It would work and stay in 6th (until, of course, it had to change for understandable reasons). Tolerable, but unnecessary resolution.

Why does this automatic transmission appear to be so inefficient and require so much manual intervention? Maybe it was engineered w/little to no focus on highway performance?