Picked up 2.0 MPG, I'll tell you how.

[turbo_bob]

Seems hard to beleve but here is what I did.

I drive H/D Dodge Ram 3500 Cummins Turbo Diesel Quad cab truck. Truck weight with shell, full fuel and me is 7000 + pounds.

I drive a combo of freeway & street miles totaling 430 miles a week. When on the freeway I drive at 2,100 RPM's, which is 71 MPH. What I did was slow down to 68 MPH, which is 2,000 RPM's. What this did is two things to up the MPG, less wind resistance and less boost, which means less fuel.

So I went from 21.5 MPG to 23.5 MPG by driving 100 RPM's less and 3 MPH slower.

[javabug]

Very cool.  However, the title of the post makes it sounds like you were gonna charge me $19.99 for a book.   

[martin]

That's what Reagan said in the 70s/80s, drive 55 to save on fuel, apparently the most efficient speed is 49mph for most vehicles.

[carapace]

Very cool. However, the title of the post makes it sounds like you were gonna charge me $19.99 for a book.

"...but wait, there's more!"

That's actually pretty impressive.  I find my gas lasts longer anytime I keep my foot out of it.  Its nice to see an actual figure in your example!

[werksberg]

That's what Reagan said in the 70s/80s, drive 55 to save on fuel, apparently the most efficient speed is 49mph for most vehicles.

"I Can't Drive 55" !!!!!!!

Sorry, a little Van Halen escaped.....

I'm getting even more better gas mileage...instead of finishing rebuilding my Full size Ford van (it came with a 5.8 L instead of the 5.0) I'm driving our back up car: 1991 Hyundai Excell and instead of $100 per week...maybe $20 every 2 or so weeks!

PS: The Mythbusters tested all those 300 mpg special carbs and gimnics and they all got less mpg that stock!

[carapace]

...PS: The Mythbusters tested all those 300 mpg special carbs and gimnics and they all got less mpg that stock!

I saw that episode, and thought it was great.  I loved the hydrogen cell thing.  THAT worked well, huh?

[turbo_bob]

That's what Reagan said in the 70s/80s, drive 55 to save on fuel, apparently the most efficient speed is 49mph for most vehicles.

No, it was Carter during the 70's fuel shortage. He also had a nationwide 55 MPH speedlimit, which lasted for years after his 4 year term. Also back then the autos did not have huge overdrive gear ratios, and 55 was good at that time. Nowdays, new cars have huge overdrives, 5, 6 & now 7 speeds, aerodynamic designs to increase MPG, 65 would be a better number to match todays cars. And cars vs. full size trucks are two different animals, (frontal area).

[lawrence]

Right on turbo bob. I drive an 86 GTI daily and I also lowered my freeway cruising speed to about 60-65mph and it helps a TON. If I have somewhere to be I step the speed up a bit.

I refuse to whine about gas prices and just laugh at all those H3's I see blowing by me in the fast lane doing a good 75-85 mph, no joke...idiots!! Might as well pour gas down the drain.

[turbo_bob]

laugh at all those H3's I see blowing by me in the fast lane doing a good 75-85 mph, no joke...idiots!! Might as well pour gas down the drain.

I have notice sense the fuel prices hit the 3.00 mark, the average mass of autos on the freeways that I drive have slowed down 3 to 5 MPH. Instead of 75 MPH, its around 70.

Those H-2's, H-3's, monster 4-wheel trucks that drive like that must get around 11 mpg.

[Bruce Tweddle]

So I went from 21.5 MPG to 23.5 MPG by driving 100 RPM's less and 3 MPH slower.

What do you think will happen if you drop it another 100 rpm?

"I Can't Drive 55" !!!!!!!

Sorry, a little Van Halen escaped.....

That's Sammy solo, before VH.

[Tom Simon]

that's good to see actual numbers like that. I've played games like that on long trips with my truck...which seems to get gallons per mile rather than the other way 'round. I found it cheapr to burn premium than regular, and it has more towing power up hills. The computer must retard the timing with regular and reduce effeciency or something. Give a guy curiosity, a calculator, and a long boring drive and it's amazing what he will come up with. And here I though I was the only nerd that played with stuff like that, I see I'm in good company

Other intersting stuff, economics of fuel economy. Question: Should I get rid of my sort of gas guzzler and buy a new fuel mizer?

I had this discussion with a friend the other day, again, I pulled out the calculator. As my CPA says, "the numbers will set you free..."  gotta love accountants

I considered my 10yr old commuter that gets 24mpg RMPG (Real Miles Per Gallon) not some EPA "with a tail-wind-and 0 weight oil test",  mpg the way I drive, commute, city, and hiway combined.

my car should last another 100,000 miles if I drive it easy and maintain it, and she doesn't pop a head gasket... She's on the tail of the depreciation curve for sure, but still looks and runs good.

the new car I could buy gets 32mpg, oooooooohhh! that so good the guy at the gas station might have to pay ME when I fill up!

With gas being $3.20/gallon, at first blush the new car seems to be the hands down winner, but wait...

My current car is worth about $5k today. After another 100k miles, maybe $500 if she still runs. $4500 in depreciation. To drive another 100k miles in my current gas guzzler (24mpg), it will cost me $13.3K in fuel plus $4.5 depreciation. She's old so let's say I have some high repair bills, $7k in repairs over and above the normal tires, shocks, and oil changes of the new car...
about $25k to drive my old car the next 100k miles.

to drive that new gas mizer, that cost $30k now and might be worth $10k after I put 100k miles on it. $20k to in depreciation. It gets 32mpg (using the same formula)
It would cost me a whopping $31k to buy and drive a new car the next 100k miles!

My math just shows there is more to the overall picture than mpg

Run the same formula substituting a new Toyota Corolla 1.6 liter and a new Toyota Prius...

[Tom Simon]

What do you think will happen if you drop it another 100 rpm?

Bob's ten minutes late for work and the boss docks him $10 pay for a net loss!  LOL!

[werksberg]

That's Sammy solo, before VH.

Opps.......I'm more of a "WHO" fan.....it was the 70's guys.....

[veloracer]

I've reduced the speed as well and picked up nearly 3mpg.  I have an '04 Mitsubishi Lancer Ralliart.  It has this valve timing thing called MIVEC http://www.theautochannel.com/news/2003/11/02/171934.html, when I am at 75 MPH, I am hitting above 3500 rpms.  MIVEC kicks in at that RPM, thus a different cam profile and more fuel.  When I drop my rpms to below 3500, I am using the lower profile and gained alot better fuel economy.  I can do about 72 MPH at around 3450 RPM, save a lot on fuel since I drive 80 miles round trip to work.

Although usually in the summer I'm driving the bug, which doesn't get as good gas mileage.  The Mitsu gets around 24 - 25 combined while the VW gets around 23 total (my right foot has a lot to do with that) 

[turbo_bob]

What do you think will happen if you drop it another 100 rpm?

It would get better MPG, right down at 1600 RPM's where peak torque is at, which is around 55 MPH, but I cant drive 55 !

[Dean N]

i heard on the radio the other day as i was flipping channels and heard mention of 55mph being implemeted again for hwy speeds.

i remember driving for years at that speed.. it sucked big time...

[turbo_bob]

I checked my trucks MPG pulling the 18 ft. enclosed trailer, 6,000 lbs loaded. The distance is 425 miles from my house to SAC and another 425 back home. I drove at 1,900 RPM's, 64 MPH with the cruse control on both ways. I got 13.61 up and 14.49 back, an average of 14.05 MPG. I used 60.55 gallons of diesel at $3.40 a gallon, $205.87 total. I made it without stoping for fuel, a 34 gallon tank.

My weekend breakdown of costs to take the family to SAC was:

Diesel: 205.87
C-16:    20.00
Hotel:  271.62
Race:    90.00
---------------------
spent: 587.49
won: 1000.00
--------------------
extra: 412.51 + a 1,750 L bottle of Puerto Vailarta Reposado Tequila, 100% Puro De Agave 

Weekend of winning,   PRICELESS !

[Tom Simon]

one hellava payday... there's nothing like drinking free good tequillia! Congrates on the Super Comp win!