Crazy Bad MPG

Why is my mpg bad?

Stock 2018 4x4 not towing, I just got 12.7mpg by hand calculation.

Answer: I have a company provided truck to commute in, the 18 is driven only on the weekends and have been mostly short local trips and I like to go quickly. That 4.3 to 1 gear ratio plus 6 speed transmission is great for towing but not using it as a car. Plus only a 1/2 tank to fill for the hurricane heading out way.

 

I'll have one free lunch, plz.

 

OP needs to check his muffler bearings and blinker fluid...

 

Thank you guys for all the input, even though I wasn’t the OG poster lol. I wonder if the TRD CIA and tune would help minimize the MPG drop?

 

My recent trip, 24 limited with off road package, 19-22 mpg average, lots of mountains & haul ass. Uhaul motorcycle trailer and 700lbs bike mostly flat roads @ 70mph or so Saturday, dropped to 16mpg. Not great but not bad either.

 

Most mpg fluxuation comes from driving habits.
Drive like a grandma and you'll average 22+mpg easy.
Drive it like you stole it and get 15mpg at best.

Velocity is squared in wind resistance. For you non-math nerds, that means going from 50mph to 60mph is an almost 45% increase in drag, and going from 50mph to 70mph almost DOUBLES your drag. Going 87 TRIPLES your drag. (For some of you doing math is also a drag) These are very simplified examples, but hopefully it helps understanding. The faster you go the faster you lose mpg.

I regularly run at the posted limit, ride a couple car lengths behind tractor trailers when I can and start coasting any time I see traffic far up the road slowing. On a bad day I get 22mpg, I repeatedly hit 25mpg, and my all time high was 26.4mpg.
I've got the 2023 Limited regular V6.

 

I'd say he needs to get a new motor for the terrible MPG.

 

Got up to 27mpg on the screen, 25 total for the trip…highway at 65-70ish

 

No doubt all downhill with a tail wind

 

Haha close…I did cheat…no air conditioning, driver side and rear window down about 1/3.

 

If I ever become concerned about gas mileage I’ll go to the dark side and buy a Prius, Tesla or ride my bike etc. I’ve never understood the hype about gas mileage. If your worried go buy an electric vehicle or use public transportation otherwise what does worrying about it or constantly adjusting actually do for you or the vehicle? I need to get to work, get my kids to sports/activities, get groceries etc and it takes gas. I drive see it’s close to empty then fill up and drive on again into the next week and repeat. Maybe gas mileage is more for those awkward conversations starters topics like the weather. Haha.

 

A penny saved is a penny earned

 

When I first retired I took that saying to heart as saving money became my only way to actively "make" money. I still try to be a bit aware of it but only so I can justify spending money on stuff I want to because I "saved" $1.00 on the light bill... LOL.

 

I've seen so many posts attributing going up in tire size to poor MPG. Yes, generally if you lift a truck and larger tires your mileage will go down, but there are some things you can do to combat this. I have a '23 TRD Pro, put 35" BFG KO2s on when new, after getting it broken in which in my opinion takes quite a few miles (5000+), I got 20MPG with normal highway driving at speeds of 70mph or less when its not windy. If there's any wind (cross or headwind), MPGs generally drop 2-4mpg. Also, tire pressure is huge and is directly related to the rolling resistance of your tires (tire weight doesn't mean anything), if I run my 35s at 42psi vs 50psi, there's a 2MPG difference right there. Also, I have added a leveling kit and rear springs, so front was lifted 2.25" and rear 1.25", as you go up in height, it does create more cross-sectional drag vs running lower profile, this is why they put retractable spoilers on all Tundra models except the Pro. Also, being I went from a 33" stock tire to a 35", that created a 3mph differential, so this throws off the MPG estimate on your dash, in my case if you do the math, my truck is traveling 8% further than it thinks it is, so when its estimating 18.5 MPG, that's actually 20 MPG in reality. I'm just trying to make the point that lifting and going up in tire size doesn't necessarily destroy your mileage, and the weight of the tires doesn't mean a thing, its all about the sidewall, rolling resistance, and how much form drag your truck has.

 

Question for those that went up.in tire size, generally what pressures are you running now with larger heavier tires? I went from the stock 265/60R20 to a 285/65R20. I'm sitting at 45psi now, was debating on 50 or so. Tire max is 80 but they will never see that.

 

go for it. Takes some of the squishy, wandering feel out of them.

 

I expect running that high of a tire pressure will gain a little MPG but also cause your tires to wear in the center more than the edges.

 

That's true and while over inflation may make the handling feel bit crisper (depending on the tire) it will also make the ride feel harsher and will likely reduce availible traction. Bottom line: No good way to get around the various downsides of taller, wider, heavier tires. That doesn't mean they aren't worth it as their advantages can easily offset the disadvantages in some situations but there is no getting around that there's downsides to them beyond their initial cost to buy.

 

Good info, from what I can tell so far, which has only been about 1/2 tank of gas, I've lost about 2mpg. But it'll take time & travel to get an accurate number.

 

You made MANY valid points here, and I agree with all except for one.
To say that the weight of the tire, or wheel and tire combo, doesn't mean anything, just doesn't fly. It's physics and you can't get around it. It's the reason racing wheels are considerably lighter than non-racing wheels. Unsprung weight is the enemy of performance, whether you're racing, or trying to get better mileage. It will always take more power, and therefore more fuel, to get a heavier wheel and tire up to speed.

 

Average by Hand each tank … I think you will be surprised.

 

The only time I see 21.5-22mpg is if I keep it at 55mph on the interstate which out West I never do. At 85 mph with a soft tonneau cover and stock tires and everything (non-TRD off-road) I get 18.6mpg. I put a soft-topper on with an integrated frame and large square cross bars (for a RTT eventually) that stick up above the cab and I now get 14.8mpg at 85mph. I also think the softtopper canvas is creating a sail/parachute effect as air comes around the cab it crashes into the side of the softtopper and I see the sides get sucked/pushed inwards creating pockets by the rear frame pillars. But I digress needless to say I'm getting rid of the topper eventually. I was happy with 18.6mpg @ 85mph with the tonneau cover though.

 

There’s method to the madness. load range E tires will require more pressure to carry the same load as a load range C tire. This will vary based on size and construction of tire as in 10 ply vs stock shit ply.

 

But remember we're talking about the delta of stock tires & wheels vs whatever you're replacing them with, you're not adding the total weight of the larger tires & wheels, in my opinion its not that big of a difference.

 

I was shocked how big a difference it is. Stock mildpeaks are 37lbs, 34.6” ko2’s… 63 lbs. 26 lbs per corner!

I have 285/65/20 as well. The chalk test liked 37 lbs so that’s where I’m at.

 

Sure, definitely heavier, I'm not disagreeing with that, what I'm saying is how much weight does it really take to impact MPG, you're talking about a 100lb delta here, for example my Pro has a 32gal fuel tank, do I feel like it gets better mileage when near empty vs full? Fuel is 6lbs/gal X 32 = 195lbs. Also, I have added a 1000CL bed slide to my truck, that thing weighs about 134lbs, I didn't see a noticeable drop in MPGs after adding that, I just don't think adding dead weight has the impact many think it does.

 

This is really interesting data.
Is the Tacoma a 4 cylinder or the V6?
I’ve looked at 3rd Gen (I like them) but can’t depart with my V8…Friends I have say their 3rd gen gets 14-15, bout like the V8…but there’s people getting 20+ on here , which is almost 1/2 the fuel cost
Interesting stuff!

 

OK, here's why I mentioned physics before, but didn't explain well enough. It's not dead weight, it's rotational weight.
Without getting into the weeds with the math, rotational weight is roughly factored as 1.5X to 2X "dead" weight.
So that 26# delta example that @MaineTundy gave is actually closer to 39 to 52 pounds per corner, so 156 to 208 pounds total.
Obviously that still doesn't tell the entire story, because as you stated, we can tote around that much or more in the bed and not notice a difference in fuel economy.
What I'm saying is, there's more going on there than just the additional weight of the tires would suggest.

Even if you completely ignore all of the anecdotal evidence presented on just this forum, where dozens of guys have noted a ~2 mpg drop after upsizing tires, (and yes, a good portion of that can also usually be attributed to increased rolling resistance) you can't ignore physics.
It doesn't lie.
OK. I'm done.

 

What you're describing as rotational weight only has an effect when accelerating, it doesn't have any effect at cruising speed, but sure would increase slightly amount of fuel needed to get up to speed.

 

v6