MPG Repost - You Get Terrible MPG Because

Lots of posts on MPG lately, so here is why you get what you get. I wrote this a few years ago and the link is in my signature to get to the original post.

I've been wanting to write on this topic for awhile now. I will try to keep it short, but that's a tough ask on this topic. I am writing this in layman's terms for ease of concept understanding so there will be minor errors, like weight versus mass. I know this is old news to some of you, but, judging by the number of mpg threads, it will be new news to others!

It seems every other day there is a new MPG thread that pops up here, and that's fine. People, especially new guys, are concerned about their new truck's efficiency and want to make sure there is nothing wrong with it. The response "If you wanted good gas mileage you should have bought a Prius" is absolutely correct. However, they bought a truck and want to know if their vehicle is in line with other trucks like theirs.

Those same threads also have posts like "My other truck has 395 HP and it gets the same gas mileage as my Tacoma!" Well, I am going to explain that too. Let's start with efficiency:

Efficiency
Guess what... your new Tacoma's engine sucks with respect to efficiency. The good news? So does every single other internally combusted gasoline engine from every single manufacturer. The AVERAGE thermal efficiency of a modern gasoline engine is around... wait for it... 20-25%. That's it. Whether it's a Ford, GM, Toyota or Dodge, every single one of their engines are terribly inefficient. This means that, for every gallon of gas you pump in to the tank, only about 25% of the energy contained in that gallon of gas gets used. The other whopping 75% is wasted, in heat! For comparison, an electric motor is about 90% efficient! Which is why it kicks ass in the mpg department. So what do manufacturers do? How come competing vehicles get a bit more mpg? How can we fix this? Why are we not driving electric trucks? Why does my underwear twist? Well, here are some answers:

The Tricks
So now you know gasoline internal combustion engines suck with respect to efficiency and diesel has its own problems, like acceleration, environmental, etc. What makes a Ford Truck get better mpg than a Tundra for example? Well, every manufacturer uses "tricks" to improve the overall efficiency (mpg in this case) since they can't improve the inherent design flaws of an internal combustion engine (we will call it ICE from now on). Here are some of the tricks:
1. Atkinson Cycle
2. Stop Start tech
3. Cylinder Deactivation
4. Turbo
5. Supercharge
6. Aluminum Construction
7.Etc
So these are the main tricks manufacturers use to improve a vehicle's mpg. Even after over 100 years of design, the engineers still can't improve the efficiency beyond about 25% without resorting to the above tricks. Each of these tricks have good and bad points. The good points are they improve mpg and in some cases give you more hp. The bad points are reduced reliability and durability of certain components, increased complexity plus increased cost in some cases. But, they do help increase mpg and that's what the average guy wants right? Now, let's move on...

Why My Tacoma Gets What It Gets
So, yesterday I read a post where the guy couldn't understand why his 350 hp full size truck got the same mpg as our 275 hp mid size Tacoma. How can this be? Sorcery? Black Magic? The answer is quite simple lol. Now, if you don't get anything else from this article, please retain the following for your future conversations:
More horsepower only makes you go faster. Boom. Let me say it again: More horsepower only makes you go faster. Got it? Let me explain in more detail:
If you have a Hellcat (700+ hp) you will have better 0-60 mph times than our Tacoma with 275 hp. No brainer right? However, even with 700+ hp, the Hellcat gets better highway mpg than our Tacoma! This is not an apples to apples comparison though. Another key point: In order to make a comparison, you must understand the differences between vehicles. For example, our truck gets around 20 mpg. A v6 Chevy Silverado Crew Cab gets about the same. If you look up the F150 Crew Cab eco boost V6 (twin turbo) 4WD it gets one mpg better. The GM mid size twins get about the same. Point is, they are all really close to the same efficiency and yet they use different "tricks" shown above to get there. How is this and why am I comparing full size to mid size?

The Physics
I am going to use round approximate numbers for clarity. Our V6 Crew Cab 4WD Tacomas with a coupla people weighs about 5,000 lbs. Guess what... so do the full sizes and other mid sizes! Yeah, our trucks have grown into big heavy pigs, but so has everyone else's trucks. Safety is the reason, but that is a topic for another conversation. That 5K weight is a problem when it comes to mpg. Why is weight so important? Now, following is another key point:
What influences MPG
1. The vehicles mass (I am going to use weight because... gravity duh)
2. Drag (aerodynamic drag and also rolling resistance of tires)
3. Driving Style
4. Geographic Location (Sea level, mountains, flat, hilly, etc)

So above are the four key reasons you get what you get, mpg wise. If you take a stock 4WD Crew Cab Tacoma, you will get around 21 mpg on highway. You get 21 mpg because of the reasons above. It takes about 57 horsepower to maintain 70 mph on flat ground in a 5K lb truck. 57 horsepower. Now, to GET to 70 mph is where the horsepower is needed! What this means is, ANY ICE vehicle that weighs 5K lbs and has similar aerodynamics driving similar terrain is going to get around 21 mpg. Ford, Dodge, GM, turbo, Cylinder deactivation, whatever. The key is 57 hp to maintain 70 mph. If it takes 57 hp to maintain 70 mph, you are going to get the same mpg. I could go into the formulas now (how I calculated 57 hp for example) but I don't think that would bring any clarity and suffice to say these numbers are close.

So, there you go. As you can see above, your vehicle's weight, drag, driving style and geographic location are what influences your miles per gallon. If you want to get better mpg,
1. Don't add weight. Weight is a killer for mpg
2. Don't mess up the aerodynamics any more than they are by lifting or adding a winch up front.
3. Drive conservatively

To Close
Now, is there a truck out there that addresses the fundamental challenges of efficiency that I listed above? The answer is YES! There is a truck currently being produced that is lighter, more aerodynamic and is 25% more efficient than our trucks! So if efficiency is your jam, I present

 

well this thread sucks, you didn't even tell me why my underwear twists..

 

New title recommendations:

I USE TOO MUCH GAS BECAUSE I MAKE BAD DECISIONS!!!1!

/THREAD

 

You get terrible MPGs because it's July your A/C is on max and there are 2O traffic lights you encounter between taco bell and back.

 

He's smart.

 

I get 17 mpg because I work 5 miles from my house on surface streets. Freeway is 7 miles.

 

Yeah, but, thats like, not my fault.

 

The last time I looked (probably 2-3 months ago) I was getting around 18 mpg and that's fine with me. I didn't buy a truck to get great gas mileage.

 

Do I win?

 

lets leave Taco Bell out of it

 

MPG threads really only have any weight when it is a sudden and unexplained drop.

Not because you wanted fat ass tires or suspension, or to load your truck up with everything and the kitchen sink then stick a giant wind sail on top.

 

Fake news, you didn't even cover gearing. Kidding!
I know my MPG sucks because I like the way it sounds when I push the pedal on the right all the way down. lololol

 

Reasons why i get shitty mpg
12 ply cooper stt pro's
Steel rear bumper
Lift kit
I keep ect on

 

I had a 14 4R with good MPG. I added bigger tires and a 2 inch leveling kit and decimated my MPG. Last year I picked up a 19 Taco and vowed not to make that mistake again. I’m stock all day errr day. I’m not very bright, so it never occurred to me that height and weight changes would fug my MPG all up.

 

I think all the complaints come from the fact that the sticker at the dealership says “20 city 24 highway” and then anyone who goes over 50mph on the highway gets <16 mpg

 

I believe the most fuel-efficient truck in the Mid-Sized Truck Category is the Ford Ranger, would not want one though.

 

This post should be " I save gas by buying a TACO" or "Don't buy truck if you want to save gas" knowing that I will not save any money, because of all the mod, I put into it.... Dammmm... those "GROUP BUY" …. Hey "Where can I find a good deal on switch panel SPOD and seat covers...etc..." I know July 4 is around the corner???

 

Thanks for the write up @hiPSI . I get basically sticker mileage, but then again I'm factory stock and a very conservative driver. If you lock out 6th gear, ECT on, 70+ mph, larger diameter tires(heavier too) you will be lucky to see 16 mpg or worse. If I take my stock OR and pull a small boat at 55mph up and down some hills in our typical IL prairie wind with ECT on and in 5th gear I get 14 to 16 mpg. I'm OK with that.

 

Engine is a 4-banger. Nope.

 

I would buy every other available truck before a Ridgeline or Ranger, both are extremely unappealing for different reasons.