Most efficient speed?

[1engineer]

All things being equal, your drag is going up exponentially according to v^2, so the faster you go, the increasingly worse your Toyota-shaped brick will do fuel economy wise.

Drag force is squared. Force required to overcome that drag is fv cubed.
Power
The power required to overcome the aerodynamic drag is given by:

P (power) = (1/2) rho A Cd v3

where rho = air density = 1.28 Kg per meter3

A = frontal area of car = 2.5 meters2

Cd - air drag coefficient = 0.32 (unitless, typical)

 

[Pinky]

Who the heck drives 55 on the freeway....

I do 55 in my Mercedes at nights when traffic is lite.

 

[Sundog7121]

[MENTION=98371]Lederman[/MENTION] (I'm now the guy I used to flip off). .

What a coincidence. So am I. :hurt:

 

[JB.]

I tried searching for the answer without luck.

What is the most efficient speed for fuel economy given level ground and 65 degrees outside air temp?

I have the tires set to 35 psi.

If you're as interested in squeezing mpg as it appears, stay away from cruise control -- at least set and forget CC. Real world efficiency at 45mph instead of 55-60 is probably less than drag numbers would suggest due to the torque converter unlocking (or downshifting) so easily at 45mph, especially if using CC.

 

[Lederman]

I heard those tiny little Fiats only get about 30mph.

You are correct. I think she sees 32 in town.

I don't "set and forget" the cruise control. I've gotten to a point that it is habit and I use it to maintain perfect speed while disengaging long before red lights and other traffic issues. Not to hilly around here and hardly ever is there a road we're on for longer than a mile. I also accelerate in a very controlled manner.

We are really lucky with short commutes and light traffic almost always.

Thanks for all the comments.

 

[diverscale]

Love that comment about using CC in town. Does not compute for most of us I imagine.
I like to get good mileage but I'm not driving slower than the posted limit to achieve this. EVER!
My numbers are slightly better than [MENTION=51186]philsey[/MENTION] 's
25 @65-70 (65 limit hwys) and 22 @ 70-80 (70 limit hwys)

I heard those tiny little Fiats only get about 30mph.

I have to raise the bullshit flag for 25MPG at 65-70mph.

Sure, you may get a instant reading, or a 1-way reading so high, but an average of 25MPG at those speed is not attainable, per my experiences due to our 5.25$/gallon gas, with our trucks, even with E0 gas. This is 9.40L/100KM for god's sake.

22MPG at 70-80 is also pretty hard to believe if you mean "average" considering you have a 4X4.

 

[thebwlife]

I have to raise the bullshit flag for 25MPG at 65-70mph.

Sure, you may get a instant reading, or a 1-way reading so high, but an average of 25MPG at those speed is not attainable, per my experiences due to our 5.25$/gallon gas, with our trucks, even with E0 gas. This is 9.40L/100KM for god's sake.

22MPG at 70-80 is also pretty hard to believe if you mean "average" considering you have a 4X4.

I've have gotten close to 22 avg on my recent trip to co and back. Stock SR5 4x4. Here is a pic of my latest mileage - omit the 16 cause 150 miles of that was in 4L or 4H on trails. The latest 19.8 is my normal average around town.

Here is my mileage chart since buying with 11 miles on the 4Runner. Notice the upward trend as the engine loosens up.

 

[Lederman]

I've have gotten close to 22 avg on my recent trip to co and back. Stock SR5 4x4. Here is a pic of my latest mileage - omit the 16 cause 150 miles of that was in 4L or 4H on trails. The latest 19.8 is my normal average around town.

Here is my mileage chart since buying with 11 miles on the 4Runner. Notice the upward trend as the engine loosens up.

What app are you using?

 

[thebwlife]

What app are you using?

Road trip on iPhone

 

[Lederman]

Thanks

 

[2013Trail]

No idea. But I'm seeing 18-19+ average mpg in my TE just driving like I normally do. I think that's pretty good.

 

[1000MPH]

I have to raise the bullshit flag for 25MPG at 65-70mph.

Sure, you may get a instant reading, or a 1-way reading so high, but an average of 25MPG at those speed is not attainable, per my experiences due to our 5.25$/gallon gas, with our trucks, even with E0 gas. This is 9.40L/100KM for god's sake.

22MPG at 70-80 is also pretty hard to believe if you mean "average" considering you have a 4X4.

Those numbers are under good conditions but can be consistently achieved.

2010 Toyota 4Runner (Toyota 4Runner) | Fuelly

I just got new tires and will be taking my first road trip with them next month. Hoping for decent results.

 

[scanny]

I have to raise the bullshit flag for 25MPG at 65-70mph.

Sure, you may get a instant reading, or a 1-way reading so high, but an average of 25MPG at those speed is not attainable, per my experiences due to our 5.25$/gallon gas, with our trucks, even with E0 gas. This is 9.40L/100KM for god's sake.

22MPG at 70-80 is also pretty hard to believe if you mean "average" considering you have a 4X4.

I got consistently 9.6 l/100km (24.5 mpg)when I was driving through New York State. Looks like nobody was speeding there, so I was driving with the flow at 55-60 mph. But at that time I had stock tires and didn't have thule crossbars with kayak rack on it.

 

[ZO6_Vette]

Tested: Speed vs. Fuel Economy - MSN Autos

Dont know if anyone posted this but here is a link testing MPG at different speeds.

 

[diverscale]

I've have gotten close to 22 avg on my recent trip to co and back. Stock SR5 4x4. Here is a pic of my latest mileage - omit the 16 cause 150 miles of that was in 4L or 4H on trails. The latest 19.8 is my normal average around town.

Here is my mileage chart since buying with 11 miles on the 4Runner. Notice the upward trend as the engine loosens up.

Well that pretty much proves what I said, as your average without your 4x4 16mpg tank is 21.65mpg. I do not think 25mpg is realistic at 65-70mph.

 

[Lederman]

Tested: Speed vs. Fuel Economy - MSN Autos

Dont know if anyone posted this but here is a link testing MPG at different speeds.

Thank you.

 

[Telepi]

In my normal everyday drive, about 90% highway with bumper to bumper rush hour coming and going in certain areas and 10% side streets with a few stop lights, I'm seeing 20.5 mpg.

I got excited one morning last week when the MPG kept going up and hit 24. The remembered reading here if you mess with it on a partial tank, it will give false readings. So at my next fillup, I reset it and left it alone.

I'm pleased with 20 mpg. It's coming in on the high side of what Toyota showed on the sticker. My H3 always was coming in on the low side at around 16 mpg. Anything over 60 mph just sucked the gas right out of it. It had absolutely no aerodynamic qualities.

 

[thebwlife]

Well that pretty much proves what I said, as your average without your 4x4 16mpg tank is 21.65mpg. I do not think 25mpg is realistic at 65-70mph.

I drove most 80-83 cause the speed limit was 75 in most of TX, NM, and 70 here in OK.