TRD OR 4x4 Auto - MPG & Auto Continuously Shifting - My Finding from a 1500 mile Trip

Yes I know. A TON of threads on the Auto Transmission and MPG, BUT .....
I want to post my findings on "MY" TRD OR 4x4 Auto after trying different driving styles and varying speeds on a 1500 mile trip. Again, this is how "MY" truck performed. Yours may be different based on altitude, posted speeds, terrain, extra equipment etc. Mine does NOT have an air dam or tonneau cover and is completely stock. I did take the truck out for a test drive before buying it, but I did NOT take it on a trip to experience the shifting, during the test drive we only had a straight section of highway and city and NO HILLS.

On my normal drive to work to Dallas, Texas at posted 75mph, I usually average 16mpg, and the auto tranny, shifts constantly from 6,5,4,5,4,5,6,5,4 etc. My drive in, is 57 miles one way, and there are about a dozen overpasses. Every overpass the transmission will either shift to 5 th or quickly downshift from 6 to 5 to 4 in order to maintain the cruise speed of 75mph.

The recording of mileage/speed for the TRIP
(Note: Cruise was used always when possible)

The recording started with my work week back and forth to work March 21 to March 24: the mileage on the odometer after those 4 days was 8469 miles at 18.2mpg. I drove 70mph on the i30 for those 4 days even though the posted speed is 75mph. I then left home bound for Louisiana on March 25, 2016. The ambient temperature outside ranged from 55F - 80F clear skies. The trip was from Dallas, Texas to Shreveport LA along the i20, then south on the i49 to Lafayette. Then down some secondary highways for another 45 miles. Return trip followed the EXACT same path back to Dallas. Total mileage was close to 1000 miles for the trip to Louisiana and 450 miles for the first 4 days driving to work. There were less than a dozen overpasses, and basically the road is straight, but it does have a few hills.

The posted speeds for the i20 and i49 are 70mph & 75mph in different sections. The secondary highways were all posted at 55mph.

I left Dallas at 9:00am March 25 on Interstate 20, and I drove at 70mph all the way to Shreveport even though the POSTED speed is 75mph. The distance was about 200 miles. For the first time I noticed that the drive was very nice; only a few times did the transmission have to downshift to 4th. Most of that stretch of highway was in top 6th gear. At Shreveport I headed south on the i49 all the way to Lafayette which is about 220 miles. I drove 70mph even though most of the posted speed was 75mph. I again noticed that only 4 times in a 3.5 hour trip south that the tranny shifted into 4th gear. I then traveled the secondary highways at 55mph, and I had NO problems with the auto almost always staying in 6th gear.

On Sunday March 27, I drove back EXACTLY the same route with the EXACT same speeds coming down from Shreveport to Lafayette. The only difference was I drove at the posted 75mph going home from Shreveport to Dallas.

My Findings.

The first 4 days of the work week; the mileage greatly increased from 16mpg to 18.2mpg, by simply decreasing the speed 5mph from 75mph to 70mph.

The trip to Louisiana from Dallas really saw an increase in mileage when maintaining a 70mph speed instead of 75mph. Leaving Lafayette and traveling the secondary highways, my wife took a picture, and for the 1st time ever the computer showed 20mpg. Much of the speed was 50mph down to 40mph based on traffic.

The trip back from Louisiana up to Shreveport at 70mph yielded about the same 18mpg.

The trip back from Shreveport to Dallas, I drove at the posted 75mph. I noticed that the tranny CONSTANTLY had to adjust the gears from 6,5,5,6,6,5,4,5,4,5,4 etc. Many of the times shifting it would STAY in 4th gear for extended times, and I would have to step on the throttle pedal slightly for it to shift. The mileage also went down to 16mpg as well. During this trip the tranny shifted HUNDREDS of times at the 75mph speed.

Summary:

(REMEMBER this is just MY TACO and it is a TRD OR 4x4 Auto, not a Sport, SR, SR5 or Limited. Everyones Taco can have different tires, air dam, tonneau cover etc. this is just what MINE did.)

I now have 10,000 miles on my Taco. I have found that the "sweet spot" for driving is in the 65mph - 70mph area. I can repeat the results and usually get 17 - 18mpg. It "appears" that trying to maintain a speed of 75mph or more, the tranny must compensate by continually shifting gears for the lack of power within the engines rpm range at that particular speed in order to maintain the set cruise speed. The effects of driving are like riding a horse as the tranny is always downshifting or upshifting. Most of the time that it downshifts to 4th gear it stays extended in that gear even though the cruise speed of 75mph is reached.

The engine has a TON of power, and I have no problem leaving an on ramp and quickly getting to posted speed. The gearing of this TRD OR and the auto tranny do not seem suited for speeds about 70mph when NOT on a flat highway without having the tranny continually shift to maintain the cruise speed.

I think the manual tranny and the different gearing would be better suited for driving at speeds at 75mph. This is JUST A THOUGHT.

Final;

My Taco is an awesome truck. I did NOT just buy it for gas mileage and highway travel. The off road capabilities and Toyota longevity were my main concerns; which are AWESOME. I will just have to drive my Taco a little slower on the highway at posted 75mph; so I don't get so annoyed with the crazy shifting. As mentioned if I drop the speed to 70mph, it rarely even shifts from 6th to 5th gear on the overpasses.

Also a proper study; would have more very detailed records of mileage and computer print outs. I did MANUALLY verify the mileage/MPG as I document detailed logs of all fills ups services etc. Also a proper study would include putting the TACO up on a wheel dyno, so we could see where the 3.5L power band was. In a proper test area, it would be interesting to see how the TACO handled the tranny shifting at maybe 90 or 95mph as the RPM would be higher in 6th gear, and that COULD be the 3.5L engines sweet power band spot. Who knows at that speed it may NEVER need to drop out of 6th gear.

I hope "MY" post helps others who are experiencing the crazy shifting to maybe offer some insight as to how to change some driving tactics or speed as well.

MY TACO is an awesome truck!

 

I like tacos.

 

This is GREAT stuff. Thank you for taking the effort to run the experiment and post your results.

I would say your detailed observations match my casual observations, so it's good to see that confirmed. My truck loves to go 50-55: super quiet and great mileage. I've also found mpg's are very sensitive to speed when experimenting on the interstate.

One thing I noticed the other day, which totally makes sense but still came as a bit of a surprise: going uphill at a higher speed allowed me to use a taller gear and bring down the RPM. Not since my '86 4x4 with 31's and a 22r have I really had to think about that. I think it's just the way of the (non-turbo, non-diesel) world now and I need to adjust my thinking.

I am a bit worried about adding drag (roof rack, larger tires, lift) because it may pull that "reasonably efficient" speed down from 70 to ??? I am tempted to try the air dam just to see if it makes a difference.

 

I thought about trying that too, but I was just in the deep south of Louisiana in Cajun country, and I took a detour down some back crawfish roads. Some were a little flooded and one had a stuck tractor in it. The amount of mud and the angle that I climbed up and out of one of the canals would have RIPPED it right off. My wife just rolled her eyes and shook her head as I took my 45K "Pretty White Truck"as she calls it and put it through the ropes of back bayou mudding it.

This is where the TACO shines! On the spur of the moment it's role changes from a highway traveler to off roader. The stock tires are "meh" okay, but the size and handling of the Taco allowed me to get around that stuck tractor whereas a full size truck wouldn't have been able too.

It would have taken a jack hammer to remove the smile from my face after my mudding. I will NEVER grow up! Took over an hour to pressure wash all the mud off on Saturday at the local car wash.

So the air dam would be great for a test for mileage, but I couldn't see me getting my lazy ass out of my seat to remove it to go down some back roads to get some fresh crawfish.

Just as a NOTE: Another test I will try in the future will be to put the Tailgate down when driving. I used to do this years ago on full size trucks to increase fuel mileage; as with the tailgate up it creates lots of drag without a cover.

 

In a nutshell:

Cruise control will downshift on Ascension. Without If you hit it at enough speed the gear will lose speed, keeping you in the same gear.

I used to do 75-80 in my 2nd gen just fine. I do 70-75 now, go figure, the extra mph made very little difference in my commute time.

I'm at about 300 miles now and loving the truck so far. Just takes some getting used to, also can't always compare it to the 2nd gen.

 

What is your conclusion again? The engine/transmission combo is aceptable? It really doesn't sound like it to me. You should drive my truck the same route.

 

It's acceptable to me. Also remember when you see the posted speed its the speed limit so its perfectly acceptable to drive at 70., just stay out of the left lane.

I don't putt along at 55 but I rarely need to go over 70, learned from my experience with the horrific gas mileage I got in my first gen at those speeds. You could literally see the gas gauge dropping at 75 and above so I would usually set my cruise at 70 (typical speed limit here) when the traffic is free flowing but my daily commute usually keeps the speed at 55-60. 3rd gen truck usually stays in the same gear unless I want to accelerate rapidly around something and even then it has plenty of power. Very satisfied with the performance of the truck based on my driving style.

No wonder I'm not bitching about how my truck drives, I rarely need to take it over 70. I have another vehicle more suited for above those speeds.

 

I see you are in Texas as well. Hello Fellow Texan! Do you drive your truck east on the i30 to Greenville Texas. Maybe some weekend take a trip to the Hunt County Fair on April 22 - May 1, and see how YOUR truck responds to the construction and overpasses at Rockwall, Fate, Royse City, Caddo Mills etc. That is what I drive, and that is where it continually shifts "IF" I try to maintain 75 mph. It would be great to know if yours acts differently. If it does then maybe some software update or reset on my tranny would make the difference. Part of the way I recorded my research was to write it up so someone could repeat the process. Granted there will be some significant discrepancies, but 70 mph from Dallas to Lafayette basically with cruise used for consistency. I do have MORE in depth logs where I recorded manually how much miles, fuel, and what speeds at where, but this write up should highlight all of that.

Is it acceptable; it is NOW after this little test. I will just have to drive at 70 mph and learn to "relax" a bit. By dropping the speed 5 mph it REALLY made that much of a difference. In reality, I didn't notice that much of a difference the past 1500 miles time wise for traveling, but I did notice I wasn't as uptight trying to constantly pass traffic. The trade off for me was that I am able to drive on the highway at a descent speed, and THEN be able to immediately go off road without any compromise. That is what I want the most! If some software or other problem is detected, and I can again drive comfortably at 75 mph then that is good too.

Another gentleman on the forum got so frustrated he traded in his TRD Auto for a TRD Manual and paid the difference. Now that I know that it will stop the CRAZY shifting by going a little slower, I am fine with it.

Please let me know if your trucks acts differently!

 

I have a 1997 Trans Am Convertible with an LT1 and 6 speed manual. It is also more suited for higher speeds. I think it would be at an idle in 6th gear at 70 mph .... LOL

 

So that explains it. Great observation and detail analysis. Basically it comes down to people's driving habits. Thanks again.

 

Have you had a chance to run non-ethanol?

 

It would be interesting to do the trip without using cruise. Seems many have stated the programming for the cruise is bunk.

 

I'm still surprised the average mpg's isn't better for this new truck and engine. I regularly average 18 mpg, year round, driving 75-80 on the highway. That's with 2009 technology.

 

I've only had my Taco for a little over 2 weeks now, but I did take it on a short road trip last week. I was in Western Oklahoma at the time and the terrain is probably similar to what you see in Texas. I found the very same thing you did. Part of my trip was in the 40-60 MPH range and I got over 20 mpg. But, once I got on the turnpike and tried to cruise at 75 mpg, the fuel economy started to drop immediately, and the constant shifting began. Everytime I started up a small incline, it would downshift and the fuel economy dropped. Where my tank average showed 20.5 for the first 60 miles or so, after an hour on the turnpike, it was down to 17! I finally took it off cruise control and that helped a little. I did the calculations for the entire tank myself and averaged 18.5, which isn't terrible for a truck. I drove it on I-35 in OKC this week at 60-65 and not on cruise control, and averaged over 20 mpg agin. What little experience I have with mine mirrors yours in that 75 is not going to be the sweet spot for mileage if you're using cruise control! Of course, mine's not even broken in yet, and overall, I'm loving the truck. I might try the ECT button next time I'm on cruise at 75 and see what happens......

 

No not yet, I am SURE it would make a difference. This particular trip I ONLY filled up at RaceTrak as I knew those stations would be available on the trip, and I wanted to keep that provider the same, and because I could get a good coffee ... LOL

Maybe someone else following this thread has tried Non-Ethanol?

 

Yes you are correct. I have done that previously. Miles per gallon are DEFINITELY better with the CRUISE OFF, but I paid 45K for a truck and the cruise doesn't work????? Also for this 1500 mile recording, I wanted to be able for OTHER people to duplicate these findings if they wanted. By using cruise set at "70 mph" someone could follow the same route and duplicate (within reason) their findings.

The cruise is controlled obviously electronically at whatever speed you select. So the ECM does whatever is necessary to maintain that speed. When OFF the cruise, I keep the pedal in the same place and when I go up a hill the speed decreases, ONCE over the crest of the hill the speed increases back up to the same speed, without shifting and staying in the top 6th gear. In the cars of yesteryear the cruise was controlled by vacuum, so the speed may change a little bit, but there was no constant shifting.

It would be nice to have a software update that allowed a deviance in speed without the constant tranny shifting issues, but in the meantime manually using for foot does just that.

 

Some of the others on this forum are posting 20 -25 mpg. Some are in Limited editions, some in SR5s, some in Sports. Some have covers, some have smaller tires, some are 4x4, some are 4x2. These are all variables.

The TRD OR version I have has no air dam or tonneau cover, and it is a 4x4; so it theoretically should get the worst mileage compared to the other models.

The posted EPA mileage was 18mpg in the City, 20 combined, and 23mpg on the highway. Those numbers are not even close to what I am getting.

 

That is an assumption, there are plenty of full size trucks with descent tires that would be able to go where your "meh" tires would take you. So many other factors play in to that as well...

Tailgate down is a myth, it does not work (been tested numerous times including myth busters). A tonneau cover is the best bet to help a tiny mileage gain. The tailgate up creates an invisible pocket (similar to a topper) to smooth the air. tailgate down creates turbulence and increases drag.

http://www.foxnews.com/leisure/2013...down-gmc-solves-age-old-pickup-truck-mystery/

Tyler

 

EPA uses non-ethanol, fwiw.

 

Food for thought Everyone!

Some members on this forum stated that the 3.5L engine we have is based of the Lexus 3.5L 338hp version. Maybe in the future there will be an ECM software update, and we can get that same type of horsepower.

Maybe a custom chip mod will become available as well.

Regardless, I will just drive a little slower and enjoy the scenery, or drive at posted speeds and NOT get the same MPG.