Vehicle efficiency upgrades: 30+ MPG in 2.5ton commercial truck

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[note:  new video has been added on step 1!]
[note 2: Most of what I write isn't relevant to Instructables.  My main blog is here:]

[note 3: Also save energy at home.  See my energy guide: ]

Go 50-100% farther on a tank of fuel.

Due to its size and weight this truck is considered a commercial vehicle and is exempt from even light-truck CAFE standards. Even so, with the modifications I have made, I am getting higher mileage than CAFE standards for 2009 cars.

I read an article in Mother Jones Magazine about Wayne Gerdes, mileage champion, and was inspired. I have read that people tend to get between 10 and 16mpg on average in the same truck I have. I was getting around 15. After the mods described here, on a recent tank I got 30.28mpg.

The best thing to do is to not drive at all. Ride a bike, take the train, carpool.
If you do drive, buy the absolute smallest car you can. If you only need a big vehicle occasionally, rent one.

I bicycle or use my 70mpg 250cc motorcycle for personal transport, but my truck still gets a lot of miles, so I wanted to make it as fuel efficient as possible.
I use this truck for work, moving up to 3 tons of soil or broken concrete, entire 1 bedroom apartments worth of belongings (including furniture) in a single trip, etc.
I also need something with enough power to move my 7500lb RV trailer (which is also my home - a very efficient way to live: I use as much electricity in a month as the average American home uses in one day)

Most of these steps could be done to any vehicle, increasing mileage from 50% to 100% or more.
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JohnMichael4 years ago
While I am in favor of improved mileage, some of the modifications in this instructable are unsafe and illegal in most places.
Care to back that up with some references? 

Coasting with the car in neutral or clutch engaged has been illegal in my state since 1971 (and is illegal in many others) -

So when I am coasting in drive with my high stall torque converter, and the rpms sit at 1200rpms with my foot off the gas, I guess you could say that's illegal, since it's not technically grabbing a gear.

Not at all - if it's in drive you are in compliance. It's coasting in Neutral and/or shifting into Neutral (or for a manual neutral/depressing the clutch) with a vehicle in motion that's at odds with the law.

Now prius drivers can finally get back at Prius Repellers (big trucks) because they can drive one and enjoy the same MPG.

Rportal4 years ago
Driving slowly is illegal. It is called impeading traffic and you can be cited. Just so you know.
JacobAziza (author)  Rportal4 years ago

Driving slowly is not illegal in a single state in the US. The posted speed limit is, without exception, the UPPER LIMIT to how fast you are allowed to drive. It is NOT a mandate that you must drive that speed, it is NOT a recommendation, and it is most certainly NOT the lower limit.

If you deliberately came to a complete stop on the highway, then you are impeding traffic.
If you were, for example, driving 15mph in a 65 zone, you could be cited for a number of things.

However, even then you are not actually impeding traffic, because on a multi-lane highway, people can just change lanes, and on an undivided country road people can pass in the oncoming lane or at turn-outs.
On city streets or mountain roads where it is not safe to pass, it is also not safe to drive 65mph, so there is no problem.

No where do I suggest driving 15mph on the highway. Below around 45 or so (depending on the vehicle) you have to shift into a lower gear, and therefor your mileage drops off.

There are some (not all) states in which there is a minimum speed limit on some highways. When there is IT IS CLEARLY MARKED ON EVERY SPEED LIMIT SIGN.
In Michigan, for example, on some freeways with a 65mph upper limit there is also a 45mph lower limit. This means you can go 20mph slower than surrounding traffic (that's assuming no one is speeding)

Bottom line is, you NEVER have to base your speed on what people around you are doing. If every single person on the highway is speeding, except you, then every single person on the highway is breaking the law, and you aren't.

Don't just make up stuff that you wish was true. Almost all laws are posted on the internet, so you can find and cite the exact vehicle code you want to inform people of, instead of spreading false rumors and confusing people.
actually it is up to police descretion as to what is an impedment of traffic (which you can be charged for) and their working model is different state to state but if you stay within 20% of the limit(depending on conditions) you won't have any problems. Oh by the way you can be charged for driving at the speed limit as well if the conditions are bad. It is called negligent driving (for not adjusting to the change in conditions). Unfortunatly if you are charged with either offence it is difficult to fight in court as I know from personal experience ( I was lucky that I hold a raceing license as well therfore my knowledge and level of expertese was considered better than the police officer's involved )
laws are different in every state. what is illegal in one state might be perfectly legal in another.
Totally not true about posted minimum speed limits. Wisconsin has a 45MPH minimum speed limit on all Interstate Highways (I-94, I-43, etc) and it's not marked anywhere on any highway sign anywhere in the state. It is the same whether you're on a 65mph zone, or a 55mph zone, 45mph is the minimum. Of course, if the MAX limit is lower, then the minimum limit is lower as well, but there's no point in going 35 in a 45mph zone.
JacobAziza (author)  dragonriot2 years ago
I'll take your word for it and stand corrected.

I don't know of any modern vehicle which has max efficiency at a speed lower than 45 anyway, so there's no reason to go below that.
Samalex676 months ago

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stephenf8 months ago
Very interesting approach. Thumbs UP!
I removed the back seat in my Saturn, but as I was doing it, I realized it weighed a whole 10 pounds. So I eventually put it back in when I needed it and never planned on taking it back out. I checked my fuel mileage a few times and it really didn't help much. It might on my Suburban, as it has a huge frame, where the Saturn frame is built into the chassis.
ImageMaker4 years ago
I was told (in connection with a failed safety inspection on my own 1990 Aerostar) that, at least in North Carolina (though likely the case in other states with safety inspection, as opposed to emission testing only) a vehicle originally sold with power steering must have the power steering in place and functioning to pass safety (which includes not having low fluid due to a leak, which is how I got tagged).  Thus your conversion from power to manual steering would be illegal here, though it might well be legal in other states.  Also worth noting that in a vehicle with rack and pinion steering, like my Aerostar, removing the power steering is a Very Bad Idea (rack and pinion feeds back too strongly to drive without power assist, except in very small, light vehicles).
JacobAziza (author)  ImageMaker4 years ago
1. The inspection mechanic/technician must raise vehicle to get beneath to
check steering mechanism.
2. The steering mechanism shall not be approved if:
(a) With front wheels in straight-ahead position there is more
than three inches of free play in steering wheels up to 18
inches in diameter or more than four inches of free play in
steering wheels over 18 inches in diameter. If vehicle is
equipped with power steering, the engine must be operating.
(b) Either front or rear springs are noticeably sagging or broken, cut,
heated or removed/missing.
(c) The front wheels or front-end assembly is bent or twisted or bolts,
nuts or rivets are loose or missing.
(d) Power steering system shows visible leaks or the power steering belt
is loose or worn or missing.
(e) Shocks and struts are part of the steering mechanism inspection.
(f) The CV joints make a popping or clicking noise when vehicle is
driven into inspection area.
[A torn, worn CV boot is not justification for failure]"

Nothing about changing power steering to manual.

Can't always trust what people say without sources, not even official people.

It wouldn't really make sense: I used an OEM manual steering gear from the exact same model vehicle, which means it is identical in every way to those versions of my truck which came that way stock.

I have only had r&p in very small vehicles (the truck is recirculating ball), so I can't comment on the potential feedback issue.

Wow, I didn't see this comment until just now.

Any case, R&P isn't only in small vehicles these days; it's cheap to make and easy to align, plus more compatible with near-universal MacPherson strut suspension. My Aerostar weighs about 3500 lbs empty, and has R&P (and, with the steering pump recently failed, is a bear to maneuver at low speed). Sure does pick up some pep without the pump, though, strongly implying I'm saving some fuel.

The clause "or the power steering belt is loose or worn or missing" is where they identify and fail vehicles that have had the power steering removed -- they'll have an empty pulley on the crankshaft and coolant pump, at least on multi-belt (older) vehicles; newer cars that use a serpentine may be impossible to match a belt for with A/C or steering pumps removed. Then again, different inspection stations adhere more or less to the letter of the law; one I used to go to failed me for a leak that didn't compromise function as long as I filled the reservoir regularly, another (the one I use now) won't, as long as the assist is working.

Beyond that, if your vehicle was originally sold with and without power steering, and you can document that, you should be fine. The same mod on my Aerostar would result in 100% inspection fails, at least with more "to the letter" inspection shops.
Inswitch2 years ago
Doubling mileage, not too shabby.

On octane, it's best to try 87 and 93 in your vehicle and do a 5 tank average of each to see which gets mileage. A blanket statement of the car being made for 87 won't benefit from 93 is not a good one to make. If tuned for the higher octane (advance timing 2-3 degrees) you may find that you get enough better mileage off 93 to more than offset the added cost. More modern, computerized vehicles have multiple octane tables that do this automatically. When the engine is started it will try the high octane table, if knock is detected it will revert to the low octane table. This is fact, I have software that allows me to reprogram my computer (EFI Live) and have altered both tables. Remember that the OEM has their own formula for setting up the engines that covers the widest range of uses, and their formula isn't necessarily the best one for your needs. I'd also recommend trying this with different brands. I have had vehicles that will get better mileage with brand A than brand B, but a second vehicle will get better with brand B than brand A, and still others that didn't care what was in the tank. I've even had two otherwise identical vehicles prefer different brands, so this needs to be checked on a per-vehicle basis. Remember when testing that fuel formulations change in spring and fall, and this will impact efficiency.

If you don't mind digging into the engine, a camshaft swap will also help. OEM cams are a balance of power, fuel economy and emissions requirements. A cam that is weighted more towards fuel efficiency would benefit. It may no longer pass a mandated pollution test, but those tests are set conditions. A vehicle that uses less fuel per mile is going to be emitting less pollution per trip.

I tried the acetone. It only worked for 1 tank, after that saw no difference. 1 tank is not enough to say it helped, so in my experience acetone does nothing for you. Once again though, different vehicles will act differently, but it was really a big pain in the backside making sure there was always some in the car.
JacobAziza (author)  Inswitch2 years ago
Thanks for that information.

I've never actually owned a car new enough to have a computer, so I would have never known or thought to try that experiment.
Great article, I have a 1994 pickup that I want to try a few of these things on. Something that should be mentioned is that even though new trucks can get up to 25 mpg now, it cost so much money and energy to have a new car built, shipped and purchased. Which is hard on the environment, yet there are thousands of cars going into the yard each year that only need a few parts. Current cars on the road longer and making them more fuel efficient is a great way to start an eco friendly movement.
Thank you for explaining the Alt delete!
JacobAziza (author)  earthwindwater2 years ago
ok, there is no way to upload pics through ecomodder pm, so send me an email
biodieselhauling (at) gmail (dot) com
JacobAziza (author)  earthwindwater2 years ago
Welcome, glad it helped someone
I'm guessing your the same person who PMd me on EcoModder?
I got your message, I'm going to take a pic before I respond
dragonriot2 years ago
I'd really like to know how much this guy spent on "Converting" his truck over time. I drive a 94 Yukon 6.5L Diesel, and I know that my current 17mpg average would go up to 36mpg with a Cummins 4BT swap.
JacobAziza (author)  dragonriot2 years ago
I assume "this guy" refers to me?

2 sheets of coroplast (grill block, underbelly, and sideskirts): $40
tonneau: $120
wood sides to tilt tonneau, from scrap wood: free
headlight covers: $10
electric fan: $15
electric vacuum pump: $290
manual steering gear: $50
buttons, switches, wire, misc: about $20
LED lights: $180
Total: $725

I may be forgetting something, but certainly under a grand all in all.
Based on how much I have driven in past years, the cost of fuel, and may change in average mileage, I should save about $2000 per year in fuel costs.
Assuming I spent all the money for downgrades upfront, it would have paid off after 6 months, (though of course this project was drawn out over about a year and a half)

Thanks for asking! Believe it or not, I actually never got around to putting all the costs in one place before. Its good to know.

vincent75202 years ago
Back to hippies days ! … Far F… Out !!!!…Get rid of everything ! …

:D :D
swoopsdad5 years ago
Actually, having been in the automotive industry for almost 20 years I feel the whole tonneau cover, tailgate up or down aerodynamics issue needs to be put to rest at last. When the box is empty the most fuel efficient state is without a tonneau cover and the tailgate(solid) in the up position. This is because the truck has a bulit-in laminar airflow to it when empty and in this configuration. Simply put, this means that the airflow created in the bed of the truck acts like a cushion to keep the airflow from the front above the bed until it gets to the rear bumper. By putting a toneau cover on(or leaving the tailgate down) it disrupts the laminar airflow creating downwards pressure on the bed(or rails) of the truck. This results in a higher drag coefficient and therefore higher gas consumption.
This would be vehicle specific. I have a 2009 Ranger. Tailgate up - 18-20MPG.
Tailgate down - 24mpg.

Oh, Mythbusters has been caught outright lying about a great many things. And intentionally skewed results from a lot of other things as well.

Great entertainment, but please do not believe anything they say. They do it for entertainment value only.

BTW, how come no one has done an experiment with the tailgate removed?
And another one with those cargo straps for a tailgate?
I HAVE, how's this for vehicle specific!
2003 Chevy S10.
I have an iPhone App that reports real time MPG via the OBD2 port.
No tailgate, 29.8 mpg!
With tailgate, 30.3 MPG!
With hard Fiberglass Bed Cap 30.7 MPG!
With thin Plastic vehicle specific,'Cab-hi Shell, 30.6 MPG.
With the tailgate and the Shell Hatch removed, 30.8 MPG.
With a round tail-cone installed and sealed to the rear of the bed and shell, lots of duct tape!, 31.2 MPG.
These tests were made at the same time, during the same commute, down the same highway and reflect the average collected during a FULL WEEK of commuting for every result!
The Saturday before each of these weeks, the battery was disconnected, overnight, to reset the computer in the truck. This way the computer relearned the trip for that week. The ONLY modifications made were to the rear of the truck.
I have not yet tackled the front of the truck! I could change the grille, the head lights, use clear tape to seal any 'dirty' gaps. remove the windshield wipers. I could really go nuts with this stuff! But the truck has the 4.3 V6 and Over-drive Automatic. I KNOW I am doing damned good with the MPGs I am getting!
omg. Are you one of those paranoid type people? They do it for entertainment porpoises only? Wow. Floored.
Do you believe dinosaurs didn't exist too?
LOL. Of course dinosaurs existed.

But Mythbusters is strictly an entertainment show, nothing more.
Fun to watch them blow up stuff.

And no, I am not the paranoid type. I am more of a doubting thomas of sorts.

If I cannot recreate their experiments with the same or very similar results, then their show is a farce.

There have been complaints with them about some of the things they show.

Maybe googling 'mythbuster lies' could be of use?
JacobAziza (author)  zolar13 years ago
I think "lies" might be going a bit far.
Sure, it is primarily entertainment. And they don't always follow scientific procedure when it isn't convenient.

But they do deserve credit for bringing the concept of "don't take someone's word for it, actually try it" to a more mainstream audience.
As a "doubting Thomas" myself, I appreciate them for that.
JacobAziza (author)  zolar13 years ago
How did you control for variables in your tests?
How many miles did you do for each one, and under what conditions?
What method did you use to measure mileage?
You are correct, there is only one modification that could be done that would make the 'tailgate up/bed empty' mileage even better! From the top of the tailgate to the bottom o the lowest part of the bumper make a perfect radius or half dome on its side. Create round Plexigalss or Lucite covers with this same radius to cover the side taillights and you will complete the laminar flow on the tail will Actually be pushed along at highway speeds!
There was a great "Mythbusters" on this that proved the same thing. Empty bed with the tailgate up was the way to go. Also the windows up with the air con on is more efficient that with the windows down. I had to adjust my driving for both of these.
JacobAziza (author)  13blue3 years ago
The problem with the mythbuster episode is that they only checked one specific model of truck, when there are many different variables of truck bed length, cab length, cab height, overall truck length and height, and cab aerodynamics.
So they really only proved it for that specific truck.
There have been other people to test and get different results. They just didn't have a popular TV show!

Anyway, what I have now is more aerodynamic than tailgate up, down, or flat tonneau, making the issue moot.

As to airconditioning, you get the best efficiency of all by having the A/C off AND the windows up. Put a beaded seat cover over white seat covers, tint the windows, paint the roof metallic silver, take off any excess clothing, and open the vents.

I love your brain. :o)
I have been turning my truck off going down hills on the free way. I can definitely tell a difference when I have my canopy on. It slows me down. With it off I have to keep my foot on the breaks to stay in the speed limit.
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