MPGs with 3rd Gen Tacomas (4WD)

So I'm a new TRD Off-Road owner (2023), and an engineer. That stupid engineering part of me is already getting nitpicky about how my planned mods will affect my unmodified MPG.

I saw a YouTube video from one Tacoma overlander that had slightly larger tires (31.5ish) and 800 lbs of stuff in the back and he claimed he only got 11 or 12 MPG. He didn't have a lot of stuff above the cab to create wind drag. Could that be right?

I would love to hear what others are seeing - especially if you have this info over time (not just one tank full - but a trip or a month or a year, etc.).

A couple of the big questions seem to be this:

Tire Size vs. MPG: I haven't heard specifics on this, but it seems like the bump to maybe 31.5" is a bit of a hit, and anything beyond that is a big hit. What is your experience.

Weight vs. MPG: Does anyone have any feedback on their experiences with MPG when they added weight?

My plan is for a modest build - slight lift, 31.5ish tires, some body armor, and some camping setup. The report of the MPG drop with added weight is scarring the crap out of me.

I'm a newbie on this site so please excuse me if I say anything out of place for this forum. And thanks for any input you have!!

 

If you care about MPG, DO NOT add significant weight. I repeat: DO NOT.

Slightly larger diameter tires, like going to a 265/70r17 or better yet 255/75r17 will not reduce MPG very much, as long as they’re not super aggressive or heavy. Keep the tires under 50 lbs each unless you want a gas guzzling dog.

Other things to avoid:

• Aftermarket roof racks
• Aftermarket skids. Get the TRD skid, it’s more aerodynamic.
  
• Different front and rear bumpers. Don’t add the weight. Also aerodynamics and air departure makes a pretty big difference on the highway.
  
• Any light bars or ditch lights.
  
• Steel sliders. (Note if you think you need sliders, consider Greenlane Offroad’s aluminum option)
  
• Regear. I guarantee someone will argue that regearing increases MPG. They’re only correct if you have added a ton of weight and are rolling around on heavy 33”+ tires. In all other circumstances, lower gears = higher rpms = less MPG.
• Tune. Again people will argue, because they have lead feet. For conservative drivers, it’ll hurt MPG.

 

Use the search function. There are hundreds if not thousands of discussions regarding this topic on this site.

Your fuel economy will drop like a rock with added modifications.

Add weight? Less fuel economy.
Lift the truck? Less fuel economy.
Add an RTT? Less fuel economy.

You’re an engineer. You know the physics behind why fuel economy drops in such scenarios.

 

You’re an engineer. You know the physics behind why fuel economy drops in such scenarios.[/QUOTE]
Eh

 

I do know the physics, but trying to find more specifics. Each vehicle responds to loads very differently. At one point in the past I had a Subaru that got about 22 MPG. I towed a trailer with my motorcycle (2000 lbs total) and the MPG dropped to 11. I had a Ford F-550 pickup (yes - it was a 550 and it was a pickup...). It got 11 MPG empty and 8 MPG towing 17,000 lbs. I have an Econoline camper van. I loaded the crap out of it and only lost a couple MPG. So different vehicles respond very uniquely. Yes it's all physics, but not so simple. And yes - I also did a search on MPG and found a lot of comments mixed in other threads but nothing specific on the topic. Maybe I need to try a different thread.

 

Keep the load 80% and BSFC will be maxxed

Tacoma's don't have enough gears

Enough compression

Enough aero

 

Hello goingplacesanddoingstuff. I appreciate the feedback, and it all makes sense. Do you have some personal experience you could share - how much "stuff" cost you how much in MPG? Thanks!

 

Does it seem possible that a guy that put 31.5" tires and had 800 pounds in the back would only get 11 or 12 MPG in a 3rd gen Off-Road?

 

This^^^^^

Also, if you want to play you’ll have to pay. Best MPG’s are stock with perhaps an aftermarket tune.

Since you are a noob, I’d keep it stock for a while and hang out here and observe and learn.

I’m stock with one tire size up and took an 1mpg hit with lighter SL rated A/T tires.

 

It seems like you’re after a table of weights and mpg loss numbers or something. That’s probably not going to happen here.

I can tell you, definitively, that adding a lift and armor and more crap will ding you at least 5+ MPG. You’ll go from ~21 to ~16 or lower.

If you want more off road capability but don’t want to lose MPG, just get 255/75r17 SL rated tires and add the Greenlane aluminum sliders. Boom, done. Don’t do more than this, even though it might be tempting. Don’t lift, don’t add more armor.

 

Weight and messing with aerodynamics will do the obvious for any vehicle.
I also think that most guys adding armor and roof racks and such are also probably the type that have a bit heavier of a right foot and get after it a little more than some of the safety freaks out there that like to lecture you for getting her sideways a lil bit and having a little fun
Getting 11-12 mph is pedal to the metal everywhere you go though, no matter the weight!

 

Thanks for the input. I would still love to get specifics from people - what mods (or weight) cost how much in MPG - and what is that MPG now. Thanks!

 

Every mod I listed to avoid will reduce mpg by 1-3, each. Your typical instagram rig, lifted on big tires with roof rack, bumpers, etc will average 12-15.

 

Steel sliders w/plates and kickout
Dual ARB compressor
255/85/16's Cooper St Maxx w/ matching spare
TRD aluminum skid
Steel mid/rear skid
Uptop roof rack
Lomax tonneau
Steel Hitch skid
LCA skids
That's it that has any weight to it.
Before mods, with my driving I averaged probably 19-20ish.
Now I average probably 14-15ish but I live in the mountains and hardly get above 50 MPH and drive short distances under 10 miles most of the time.
When on the highway to Utah I can get close to 20 MPH if I'm taking her easy.
I don't account for speedometer adjustment w/ larger tires or any of that, or do math, this is just what my CPU tells me.
"I was told there would be no math"
I don't drive crazy but I drive moderately fast and like to have fun sometimes

And I don't have Instagram This site is my only social media so to speak

Edit: also have shovel, axe, traction boards, bed mat and Hi-lift in the bed. And yes I have had to use them all at least once before. Traction boards the most

 

2+ years with my '21 TRD OR AC Auto with a Leer cap (otherwise stock) gives me this:

 

Front(winch) and rear bumper
2 1/2” lift
Sliders
Engine and transmission skid plates
33” K02 tires
Full size spare and recovery gear/tools that I always carry.
Tonneau cover
Here’s an example of my MPGs, they would vary depending on the off-roading I did:


After installing a roof rack and tire carrier my MPGs did drop another~1.5
I stopped carrying about the mpgs because I got a dedicated daily driver.

 

2019 TRDOR V6 6MT
I run GY Duratracs
235/85/R16 Winter (31.73")
265/75/R16 Summer (31.65")
DV8 Armor:
Front bumper w/ Smittybilt 9500 winch and Baja Designs 20" lightbar
Rear bumper
Skidplate (engine)
Sliders (boatside)
Baja Designs Ditchlights
Bilstein 5100s all 4 corners set to level truck

Pre-mods my average MPGs on my 42 mile commute were 21 to 23 MPG
Post-mods I average 18 to 20 MPG
MPG numbers from the truck's CPU calculations. I haven't bothered to calculate separately as the numbers I see match what I expected.

Hope that helps some.

 

Holy shit is your undergrad in a discipline other than one where you learned physics?

Look, simply put, I can write down a half dozen formulas to prove everything you say in your post wrong because....and you should know this....the laws of physics apply to everyone and everything and it's impossible to break those laws!
You post that "different vehicles do different things" like there is some mystical force out there when it comes to efficiency! Lol no. The fucking rules apply to everyone and everything.
My professors would have had you switching majors before the first week as a freshman.

However, let me answer correctly.
If you do the mods listed and you currently get 20mpg, you will be running around 14-15 mpg after mods.
Good luck.

 

I took the air dam off a couple of years ago with the intention of installing a Fumoto drain valve and TRD skid plate. I lost about 2mpg with the removal of the air dam...a good deal on the skid plate didn't come along until September of last year (and I was in-between oil changes) so I waited until oil change time (2 weekends ago) to install the Fumoto and skid at the same time...got my 2mpg back and I'm running Toyo Open Country AT III's (265-65-17's) I'm back in the 22-23mpg range. The difference between the cheap ass stock skid and the TRD is huge.

 

Totally bone stock except for one size larger tires on my sr5. Mpg vary from 19 in the winter to 22, and change in the summer. Last tank I calculated it at 22.8 mpg.