For those that are trying to stretch those dollars for fuel, here's a couple things that help...

The Steam Whisperer

On our 2007 Jeep Grand Cherokee 4wd 3.7 v-6 with around 220,000 miles that got a consistent 21 mpg highway:

Closed up the air leaks around the radiator: 0.3 mpg on highway
We changed the O2 sensors: 2.5 to 3 mpg gain on highway and definite gain in city mpg.
O2 sensors get lazy over time and start causing the engine to run too rich.
Installed 2inch deeper air dam: 1 to 1.5 MPG gain on highway.
So now we're running 25 to 26 on the highway versus 21.2 highway.

Of probably greater interest are changes to my 2017 Chevy Express full size with diesel carrying its standard 2500 lbs payload ( gross weight around 7,500 lbs), 80,000 miles

Removed the stock air dam that was about 4 inches deep in front of the tires and about 2 1/2 inches deep in the center and installed the airdam off a 2015 Suburban that is about 2 inches lower all the way across ( still 8 inches or so ground clearance)
Picked up about 2 to 3 mpg highway, bringing it up to around 33mpg at 62 mph and an incredible 35.5 to 36 mpg at 55 mph.
I am already working on a front bellypan for the van to smooth airflow under the engine and trans and maybe tire spats to help smooth airflow around the tires.

The cost of the materials for the air dams will be back in my pocket within a month or two and my labor probably within 2 month on the van and 6 months on the Jeep.

Dave Carpentier

My commute is only 20 mins at highway speed , but I have noticed savings by just slowing down from 60 to 50 mph. I've been thinking about getting a second set of rims so I could run "summer" tires and keep the "all weather" tires for winter. Not sure how long the payback would be on the rims though.

PC7060

Dave Carpentier said:

My commute is only 20 mins at highway speed , but I have noticed savings by just slowing down from 60 to 50 mph. I've been thinking about getting a second set of rims so I could run "summer" tires and keep the "all weather" tires for winter. Not sure how long the payback would be on the rims though.

Reminds me of back in the day when we all switched between standard and snow tires. All season tires are right up there with digital ignition systems along with 100k mile coolant and spark plugs  

ChrisJ

Dave Carpentier said:

My commute is only 20 mins at highway speed , but I have noticed savings by just slowing down from 60 to 50 mph. I've been thinking about getting a second set of rims so I could run "summer" tires and keep the "all weather" tires for winter. Not sure how long the payback would be on the rims though.

I think that may be very dependent on what tires you have.  The all season tires I've been using for years now are very hard rubber so they last a long time and give very good mileage.   I'd never expect any payback by switching for fuel mileage if you're using such a tire already.

retiredguy

Many, many years ago, I bought 2in1 recap tires. the 1st half of the tread was an actual snow tire and the 2nd half was a summer tire. When the snow tire wore off the summer tire was left. Great idea but the recaps were junk.

Another great idea when most all cars were stick shift (manual transmission) was to shift into neutral on any down hill trek. Wow, did we save a lot of gas and money. Gas back then was usually 25 cents however you could at times buy it for 20 cents a gallon.

Then they had the red spark enhancer. You removed the main coil wire and installed this device between the coil wire and the distributor cap. Another scam.

The best gas saver I ever found was when I shifted into "overdrive" in my 1950 Studebaker Champion convertable straight 6 cyl and was able to get 35 MPG when driving between the North Hills of PGH and Zelienople.

Let me show you how much money I saved. Wait, where did it go. Which one of you stole all my savings.

ChrisJ

retiredguy said:

Many, many years ago, I bought 2in1 recap tires. the 1st half of the tread was an actual snow tire and the 2nd half was a summer tire. When the snow tire wore off the summer tire was left. Great idea but the recaps were junk. Another great idea when most all cars were stick shift (manual transmission) was to shift into neutral on any down hill trek. Wow, did we save a lot of gas and money. Gas back then was usually 25 cents however you could at times buy it for 20 cents a gallon. Then they had the red spark enhancer. You removed the main coil wire and installed this device between the coil wire and the distributor cap. Another scam. The best gas saver I ever found was when I shifted into "overdrive" in my 1950 Studebaker Champion convertable straight 6 cyl and was able to get 35 MPG when driving between the North Hills of PGH and Zelienople. Let me show you how much money I saved. Wait, where did it go. Which one of you stole all my savings.

Sadly there's no limit to the amount of useless junk sold for cars, even now.

As for shifting into neutral you don't want to do that with modern cars. The reason is if you drive correctly you can get most of them to go into injector cutoff where they actually turn the fuel off while going down hill.  They can't do that if it's in neutral.

The Steam Whisperer

They do make special low rolling resistance tires. Narrower tires also help.

Slowing down is a big difference. IIRC power required increases at the square of the speed increase.

The Steam Whisperer

Here's a useful link to the Ecomodder website with a simple chart and the gains made on an example vehicles. There's lots of useful information there from aero to driving techniques and much more.

https://ecomodder.com/forum/showthread.php/drag-reduction-modifications-wind-tunnel-audi-a2-cd-21175.html

Dave Carpentier

There's also tread/lug patterns to consider. A Summer or All Season tire that is rated high for mpg is going to be hard and have most straight grooves. Terrible choice for winter, of course.

I agree on the narrower tires, I went from 265 to 245 (with a corresponding change in the ratio number to keep the circumference as close to oem as possible). You dont want to go too narrow, as you would start to loose stopping power at some point (contact patch size).

I always wondered about following distance. If we could draft the vehicle in front, it would certainly improve mileage.. but of course thats dangerous and illegal. A bit further back and you're in quite turbulent air. Further back from that the air is cleaner. Is there an advantage to staying further back than the standard "two seconds" ? How far back is clean air anyhow ?

ChrisJ

The Steam Whisperer said:

They do make special low rolling resistance tires. Narrower tires also help. Slowing down is a big difference. IIRC power required increases at the square of the speed increase.

I think that's true within reason.

Meaning if you took a decent vehicle and drove 100 miles at 10mph and then did the same trip at 75 mph I'm betting you'd see significantly better mileage at 75.

My 45-48mpg is mostly interstate speeds and I don't mean 50mph.

How the vehicle is tuned as well as the aerodynamics of it are important.  The more that throttle is closed the less efficient that engine is.  A 200hp engine producing 10hp is even worse than it producing 20hp.  So somewhere there's a trade-off between wind resistance, rolling resistance etc and fuel efficiency and you need to find the sweet spot.

That's where the pulse and glide technique comes from.  You accelerate fairly hard (not wide open) and then coast for a good distance.

I'm not saying some vehicles won't do better at 50 than 60 but I am saying some may very well do worse.

JUGHNE

Years ago, the "Drive 55 and Stay Alive" was the required fed speed limit, just about everywhere.

OTR truckers claimed that 55 MPH decreased their MPG.....but what do they know?....they are simply the ones paying to fill the tank everyday.

My 1 ton van with the 7.5 L (460 CID) 2 barrel carb, will get almost 10 MPG on the highway if it runs at 60 MPH.
Anything higher will drop it drastically. Loaded to 7,000 or 10,000 pounds total makes no difference.

It is like trying to push a large refrigerator box down the road, against the wind.
Thankfully only have to travel about 4000 miles per year.

ChrisJ

JUGHNE said:

Years ago, the "Drive 55 and Stay Alive" was the required fed speed limit, just about everywhere. OTR truckers claimed that 55 MPH decreased their MPG.....but what do they know?....they are simply the ones paying to fill the tank everyday. My 1 ton van with the 7.5 L (460 CID) 2 barrel carb, will get almost 10 MPG on the highway if it runs at 60 MPH. Anything higher will drop it drastically. Loaded to 7,000 or 10,000 pounds total makes no difference. It is like trying to push a large refrigerator box down the road, against the wind. Thankfully only have to travel about 4000 miles per year.

Going to take a blind guess 
Does your van run around 2800-3000 rpm at 60mph?

The Steam Whisperer

ChrisJ said:

The Steam Whisperer said:

They do make special low rolling resistance tires. Narrower tires also help.

Slowing down is a big difference. IIRC power required increases at the square of the speed increase.

I think that's true within reason.

Meaning if you took a decent vehicle and drove 100 miles at 10mph and then did the same trip at 75 mph I'm betting you'd see significantly better mileage at 75.

My 45-48mpg is mostly interstate speeds and I don't mean 50mph.

How the vehicle is tuned as well as the aerodynamics of it are important.  The more that throttle is closed the less efficient that engine is.  A 200hp engine producing 10hp is even worse than it producing 20hp.  So somewhere there's a trade-off between wind resistance, rolling resistance etc and fuel efficiency and you need to find the sweet spot.

That's where the pulse and glide technique comes from.  You accelerate fairly hard (not wide open) and then coast for a good distance.

I'm not saying some vehicles won't do better at 50 than 60 but I am saying some may very well do worse.




The power required follows this pattern for aero drag, but the engine efficiency obviously doesn't. In general most cars peak out around 45MPH...aero drag is still relatively low, but the engine is partially up on its torque curve so it can run at decent efficiency. It seems like alot of cars have a sweet spot at around 62 or 68 MPH. Once you start going 70mph, mileage usually seems to drop very quickly.
My diesel van is nearly at peak torque at 1500RPM ( 325 lb ft, Peak is 370 lbft at 200 rpm), so that's where GM has it geared for transmission shifts in the range from 1500 to around 2800 rpm.
When compared to the gas 6.6L v-8, I am running less than half the displacement but produce the same amount of torque at 1/2 the rpm ( peak torque is about 370 lb ft for the gasser at 3500 rpm). That's translates into incredible MPG, while having loads of grunt in city traffic.

JUGHNE

IDK RPM, no tach for 1984 Ford vans.

It is a retired ambulance.
You forced me to look thru the specs that came with it.
These are sent to a 3rd party testing facility just before delivery.
They certified it to do 0-55 mph in 17 seconds....doesn't really set you back in the seat or smoke the tires with 9100 GVW.
(that was with 4 barrel Holley....now 2 barrel Autolite)
They also stated 8.0 MPG.....reason for 40 gallon tanks.

Standard 3 speed auto with 4.10 limited slip differential......gives you the advantage that you can get farther from home with that before getting stuck in the snow.

But has the headroom that I can stand up inside......necessary for old guys.

Solid_Fuel_Man

That old retired ambulance with a 460 would most definitely have a Ford C6 transmission. While being completly bullet proof, it has lots of parasitic loss. That doesn't help your 10mpg. 

With a 2 bbl autolite, which would be a 2100 or 2150 your flow is around 200-425CFM depending on the venturi size. They are known to be economical carbs. 

Larry Weingarten

For those who ride motorcycles, I know that with good streamlining, you can at least double the mileage when going at highway speeds. No doubt more could be done with cars to get that teardrop shape.

yours, Larry

JUGHNE

As my teenage grandson worked with me and had to calculate the mileage at each fill up....on paper BTW....he pointed out a new van was in order....mine was "dated".

So I proceeded to tell him that at 4000 miles per year @8 MPG I buy 500 gallons of gas a year.
At an average of $4/gal we see spending $2000 per year. So would a new van cut that down to 200 gallons a year? So a savings of $1200.

But add sales tax of 7% for the purchase of new.

Yearly auto tax amounts to a fair amount for several years.
The annual plates/taxes for this has been $28.00 for the last 15 years.

Then interest on purchase amount.

And a little more for insurance.

And I want to be able to stand up inside....that means a Sprinter or Transit.

I have never priced a new van.

Never purchased any brand new vehicle.

The newest SUV was 2 years old when we got it.
Let someone else pay the first year depreciation.

BTY, do you know that an SUV qualifies as a work truck?
That has passed our CPA for the 2 we have.
As does the F150 we have.

ChrisJ

Larry Weingarten said:

For those who ride motorcycles, I know that with good streamlining, you can at least double the mileage when going at highway speeds. No doubt more could be done with cars to get that teardrop shape. yours, Larry

Yes but more often than not cosmetics of a car play a much bigger roll than how it functions.

The Steam Whisperer

Jugne has the biggest secret for cutting costs... cut your miles. A large number of our clients don't even own cars.. they can walk or take public transit for anything they need. A very interesting pattern emerged after the real estate crash of 2007....In the Chicago region of about 5 counties... the areas with the lowest number of homeowners behind in payments or in foreclosure were the homes located along the rapid transit lines in the city. The highest number were in the outer ring suburbs. Guess which group probably spends the least on cars? I haven't ever seen any actual numbers, but I bet the average U. S. citizen spends more money on cars in their lifetime than on their home.

Dave Carpentier

The Steam Whisperer said:

... the areas with the lowest number of homeowners behind in payments or in foreclosure were the homes located along the rapid transit lines in the city. The highest number were in the outer ring suburbs.

Interesting and is at least anecdotally reasonable, but could also just be a correlation.
The burbs contain many more mcmansions with a % of those in sketchy financial situations.
The inner city would have a much higher % of rentals.
I dont dispute that vehicle ownership is brutal. Between purchasing, insurance, fuel and repairs, it's a high price to pay for 'freedom'.
I elected to live outside of the city, love my peace out here. No public transit at all, it's drive or be driven.
According to googlemaps, I could walk to work in about 5 hours. Paying for the luxury of sitting down in a conditioned box for a 22 min drive is quite appealing.

JDHW

@The Steam Whisperer
The drag goes up with the square of the speed - power is proportional to speed cubed! That is why it is really difficult to forecast the output of wind turbines. Small errors in forecast wind speed = big changes in output.

Regards
John

reggi

retiredguy said:

Many, many years ago, I bought 2in1 recap tires. the 1st half of the tread was an actual snow tire and the 2nd half was a summer tire. When the snow tire wore off the summer tire was left. Great idea but the recaps were junk. 

The recap was one piece grooved for snow that transitioned to a summer tread when worn ?  Before radials I assume ? I'm guessing you couldn't get them studded ?

The Steam Whisperer

Dave Carpentier said:

The Steam Whisperer said:

... the areas with the lowest number of homeowners behind in payments or in foreclosure were the homes located along the rapid transit lines in the city. The highest number were in the outer ring suburbs.

Interesting and is at least anecdotally reasonable, but could also just be a correlation.
The burbs contain many more mcmansions with a % of those in sketchy financial situations.
The inner city would have a much higher % of rentals.
I dont dispute that vehicle ownership is brutal. Between purchasing, insurance, fuel and repairs, it's a high price to pay for 'freedom'.
I elected to live outside of the city, love my peace out here. No public transit at all, it's drive or be driven.
According to googlemaps, I could walk to work in about 5 hours. Paying for the luxury of sitting down in a conditioned box for a 22 min drive is quite appealing.

I think they may have been looking at just properties, without distinction of rental or owner occupied, but I don't know how to find the study again. In many of the wealthiest areas in the city, there are very few rentals...most of the former rental units are now either condos or coops. Also, the transit lines not only run in the inner city but all the way out to the inner suburbs on the West and North sides. If it was just the inner city, the fact that property values tend to be much higher there than the suburbs could of been a factor, but the transit lines run through a relatively broad range of income groups. You've got the inner city with extremely high values...some of the highest in the world ( 5 story 20 foot wide shoot gun homes built in the 1800's for the extremely wealth and still occupied by that group, homes worth 10 of millions). Then through neighborhoods that started gentrifying in the 1970's through the past 20 years, making real estate prices skyrocket sometimes by more than 20 fold in just 4 years( and destroying/displacing neighborhoods that were typically people of color that had roots there going back to the early 1900's) ( like Bronzeville, former home of the old black downtown, the former Chicago Defender Newspaper, the home of Chicago Jazz and Illinois Institute of Technology) through very wealthy and ethically/racially mixed neighborhoods like Hyde Park/ Kenwood ( Home of University of Chicago, President Obama) then through working class neighborhood and often poorer neighborhoods and then ending up in the inner suburbs ( Evanston...home of North Western University) and Oak Park ( Home of Frank Lloyd Wright) which have a variety of incomes, but by today's standards at least double or more the average U.S. household income ($35,500/year) to the very wealthy.

retiredguy

@reggi; you are exactly right. They were recaps that had a snow tread first, (no studs), that wore away and exposed the summer tread. I bought these in the early 1970's. Great idea, junk tires.

Jamie Hall

Anybody remember "sandpapers"? That was a type of winter tread soft rubber recap with a lot of sand in the compound. They were wonderful in deep snow (the aggressive tread) and packed snow or ice (the sand). But... if you got 5,000 miles from a set you were doing well, and they were almost impossible to balance.

Modern "all season" tires are... OK. They are not true snow tires, however. Some do have a soft enough rubber to be reasonable on ice and packed snow, though, and a good enough tread pattern to be very good to excellent in the rain. Off road or deep snow? Um... no. But I've got a nice yankum rope in my truck, give me a ring if you get stuck.

The Steam Whisperer

They are making real snow tires again. I ran them on my ford van in the winter and the difference was huge. I slipped off a driveway out in the country with 2 foot high drifts. Just kept the throttle very gentle, drove through the 18inch to 2 feet of snow that was everywhere and pulled right back up on the drive and drove home... with no limited slip. I believe Bridgestone brought them out first. Some of the new designs have been tested to provide even better traction on ice than studs.

I had some friend's get stuck in the winter with thier 4wd Ford Pickup. I gently pulled up to their bumper and pushed them right out.

I was running Bridgestone Blizzaks

Dave Carpentier

No matter how you slice it, there's no one best tire.
If you want high mpg, you have to get something fairly hard with fairly straight grooves.
Terrible choice for snow/ice though.
We can save money for part of the year I guess.

Solid_Fuel_Man

For my work van, 2020 RAM ProMaster 2500 159" wheelbase tall roof. I get an average of 19mpg in the summer. I bought 2 steel wheels and keep my aggressive snow tires on them and simply swap them in the driveway with a floor jack. Van is way too tall to fit in my garage. 

Winter here in the Arctic tundra...can be sub zero for weeks at a time and sometimes the van idles for long periods of time. I get an average of 15.5 then. 

My chevy express 2500 with a 4.8L was lucky to ever crest 14mpg and was literally half the size. Althougg I had a ladder and pipe rack, the promaster is plenty big enough to put my 24' extension ladder inside and full sticks of pipe in, no ladder rack needed. 

Also had an Econoline E250 with 4.6L which did about the same mileage as the Chevy. 

The front wheel drive 3.6L RAM just works well, being unibody makes it lighter than the smaller vans which I think helps the overall efficiency. When I first bought it and drove it home 400 miles, it had 30,000 miles on it. I got 21mpg going 75mph on the interstate. Now I have about 1,500 lbs of shelving and stock in it. But don't drive on the interstate as it us outside of my work area.