Drive 65mph, NOT 70mph!!!

[SkylineGTRracer]

Speed is one thing the other is to keep the RPM down in order to get the most MPG. 55-60 would be the sweet spot for you MPG minded drivers. If you do drive with MPG in mind please be aware that others, me included, aren't. There's nothing ruder or dangerous than someone hogging the fast lane going 55 in a 70 other than distracted driving. I see it a bit here in SA. As for me I average about 15-16.

 

[RonMAIDEN]

Alot of it also has to do with throttle position since maintaining 65 or 70 is going to be different at times depending on terrain and stop and go traffic. Sometimes I can maintain 65 with probably less than 10% of the throttle and other times I'll need over 50% just to maintain the speed going up in the mountains but yes doing much over 70 on any terrain is going to really affect overall MPGs.

 

[JB.]

I do quite a bit of long range (400+ miles one way) in different speed zones and the change in fuel consumption at 5 MPH intervals is pretty astounding.

Hand calculated, here are my typical averages:

75 MPH - 19 mpg
70 MPH - 20 mpg
65 MPH - 23 mpg
60 MPH - 25 mpg

You're not a little skeptical that the gap between 65-70 could be triple the gap between 70-75?

 

[8086bruce]

Wow thats great! Thanks for the info. :thanks:

 

[CelticRunner]

That's quite a difference in mileage.
One of my few complaints about the v8 is full-time 4WD, think how much better the mileage would be if you weren't always running in 4H.

my understanding (possibly more relevant in lighter vehicles) is that because full time 4 cars/ trucks dont have a heavy transfer case that the part 4 cars/ trucks do, they save weight.

Yes it takes more power/ energy/ gas to power 4 wheels over 2, but often the weight saved evens out(and again possibly not as relevant on a truck, though the TR4 is not a heavy truck)

DocMT, did you consider that driving to the mountain to go skiing is more uphill than leaving? it may not be like that everywhere, but here in MD driving east towards the Appalachian mts only goes up in elevation.

I think it is safe to say that speeds of 70+ mph are not efficient, but going 60 when the rest of traffic is going 75 is dangerous and worth the 5 bucks you'll spend extra on gas

 

[JB.]

my understanding (possibly more relevant in lighter vehicles) is that because full time 4 cars/ trucks dont have a heavy transfer case that the part 4 cars/ trucks do, they save weight.

The transfer cases are virtually identical in the 4WD 4runners whether full-time 4WD or 2WD option.

 

[thirstyturtle]

Just wanted to update you guys a bit since it seems I'm getting significantly lower mileage than some.

I reset my ECU yesterday (first time since new tires and removal of carbon filter thing) and on my drives to and from work yesterday and today I averaged 21.0 according to the comp which should be about 20.0 real-world MPGs. In the last week and a half since I've gotten tires and removed that filter I've averaged 17 real-world MPGs on this same trip. I'm freaking stoked because it appears that a simple ECU reset has yielded me some extra MPGs!

Note: since getting my new tires I've been driving much more conservatively in an effort to increase MPGs and I think resetting the ECU really helped because it adjusted itself to my new, gentler driving style.

Sent from my ADR6300 using Tapatalk

 

[midnight runner]

I think you guys aren't really looking at what's really happening. Look at the basic physics of what it means for fuel economy. As speed increases, the amount of air that the vehicle is fighting against goes up exponentially. So it takes 4 times as much energy to fight the wind resistance at 30mph than it is at 60. That's part of the reason why it's more difficult to accelerate at higher speeds.

Also, I'm kinda fuzzy on the exact specs of the 06+ V8, but if the vvti works anything like vtec in a Honda, then the cam profile changes at a certain load/rpm. Meaning the cams open up longer for more air to get into the cylinder. More air means more fuel. On the flip side it also means more power. Given it's a truck, I wouldn't be surprised if that cam profile switched over somewhere around the 1900 rpm mark. Anyone happen to know what the cam profile change over parameter are?

 

[thirstyturtle]

I think you guys aren't really looking at what's really happening. Look at the basic physics of what it means for fuel economy. As speed increases, the amount of air that the vehicle is fighting against goes up exponentially. So it takes 4 times as much energy to fight the wind resistance at 30mph than it is at 60. That's part of the reason why it's more difficult to accelerate at higher speeds.

Also, I'm kinda fuzzy on the exact specs of the 06+ V8, but if the vvti works anything like vtec in a Honda, then the cam profile changes at a certain load/rpm. Meaning the cams open up longer for more air to get into the cylinder. More air means more fuel. On the flip side it also means more power. Given it's a truck, I wouldn't be surprised if that cam profile switched over somewhere around the 1900 rpm mark. Anyone happen to know what the cam profile change over parameter are?

Why do you think we're ignoring the fact that the wind speed goes up exponentially? That fact has already been mentioned a few times and I think it's spot on.

As far as the VVTI cam timing goes, I'd be really interested as well to know if it's anything like VTEC in a Honda/Acura and if so when the profile changes.

Anyone got some good info?

Sent from my ADR6300 using Tapatalk

 

[DocMT]

As speed increases, the amount of air that the vehicle is fighting against goes up exponentially. So it takes 4 times as much energy to fight the wind resistance at 30mph than it is at 60.

It's nice to generalize, but you really can't make a definitive statement like that without also understanding that it's not that simple. Aerodynamics and frontal area play a huge part in how easy or hard it is for any vehicle to overcome aerodynamic drag (or wind resistance, as you like to call it).

If someone claims 23 mpg @ 60 mph and 20 mpg @ 65 mph, that just doesn't seem very logical. Since there are obviously other factors at play and the fact that we're talking about average speeds (since nobody can possibly run at one exact speed all the time), then it's easy to see that the results are biased. In the real world, nobody is going to lose 13% of his fuel economy by driving 5 mph faster.

 

[DocMT]

Also, I'm kinda fuzzy on the exact specs of the 06+ V8, but if the vvti works anything like vtec in a Honda, then the cam profile changes at a certain load/rpm. Meaning the cams open up longer for more air to get into the cylinder. More air means more fuel. On the flip side it also means more power. Given it's a truck, I wouldn't be surprised if that cam profile switched over somewhere around the 1900 rpm mark. Anyone happen to know what the cam profile change over parameter are?

Toyota's VVT-i isn't' the same thing as Honda's V-TEC. The Honda system not only alters cam timing, but it also alters valve duration and lift. It activates as a predetermined RPM. The early Toyota VVT systems also activated at a predetermined RMP (I believe it was around 4,400 RPM), but the newer VVT-i (the "i" is for "intelligent") can activate at different RPMs based upon several factors, mostly engine load/manifold pressure.