V8 MPG Experiment

H

Hairris

Member
So with a new job I have been commuting for the past 4 months about 60 miles(all highway) everyday. The stupid side of me was considering trading in the 4runner for something more economical.

After calling myself stupid(actually my wife did), I decided to start out on an experiment. How good of gas mileage can you actually get in a 2003 V8 full-time 4WD 4Runner with a 2" spacer lift and BFG All terrains. Keep in mind, I have seriously done no other mods to my car except the HCF delete, and normal maintenance. Always synthetic Oil....and that's about it.

I must admit, I am an agressive driver and typically want to be in the front of ever pack while driving, so this experiment has been tough......

Here's what I have done.......

I decided for two weeks to:
1. Ride with NO AC....EVER.(EXTREMELY HARD IN GEORGIA IN JULY!)
2. Never let my engine go above 2000 RPMs.
3. Let RPMs dictate my speed, not the other way around.
4. Try braking minimally, so to use momentum the best.

How'd it turn out. The only source I have considered(accurate or not?) is the 4runner's trip computer in the center console. After driving about 500 miles in two weeks back and forth to work, my trip average MPG says 20.0!!!!!!

Holy Crap? Is this thing accurate.

I was also doing some other calculations because of bigger tires and figured that my 265/70/17 are 3.4% bigger than stock, and with that calculated in to the calculations the computer can't see, it comes to about 20.68MPG.

Am I being Naive to think this is correct. Seems like a great problem to have!

ANYONE ELSE WANT TO TAKE THIS CHALLENGE AND SEE?
 
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I just did a 1300 mile all interstate trip over the last weekend (mix of 55,65,70 mph zones). This last trip I tried only 5mph over with smoother accels, attempt to use no brake as you did. I got low 19's on the trip computer verified by the math out to 19mpg! This is in a 07 V8 awd, 2" lift, stock sized tires, HFC delete. I've found the other factors are ambient temp/wind obviously, my economy improved when I changed my diff fluids, and it seems to improve yet some more towards the end of a 5k mile oil change interval.
 
I drive very conservatively in mine. When I first got it the computer said the average on the highway @70mph was 16mpg.

Once I changed the oil to synthetic, changed the both diffs and transfer case with M1 and inflated the tires to 40PSI I now average 20mpg @70mph.

I usually only do 5mph over the speed limit especially on long road trips.
 
The computer will read about 2.5 mpg higher than actual when calculated. Not sure if that is true for everyone or every year, but most everyone I have seen report it says the same. I get 19.5-20 on the highway in my V8
 
i commute 350 miles a week in mine. I have to stay at 70mph and accelerate normal. Keeps me under 2k RPM and i get 16-17MPG. Anything over 70 and im in the 13-14mpg. Any types and all fuel octanes, ive tested them all.

My speedo/odometer is corrected for wheels/tires.
 
Relying on the trip computer on the dash won't give you accurate information. You have to log your fill-ups and your actual mileage (correcting for any non-OEM tire circumference) to get your true miles per gallon.

A useful website for logging this is: http://www.fuelly.com

Fuelly also allows you to see what others are getting in certain types of vehicles.
 
Gatafly said:
The computer will read about 2.5 mpg higher than actual when calculated. Not sure if that is true for everyone or every year, but most everyone I have seen report it says the same. I get 19.5-20 on the highway in my V8
Click to expand...

Mine is almost always 2 mpg high. I hand calculate every tank and it's very consistently off.

OP: I'm bummed when my mpg avg says anything less than 20. I did 1800 miles from one end of cali to the other last month and it read 21 almost the entire way. Hand calculated mileage was 17-19 religiously.

I'm 100% stock other than the hcf delete running conventional oil, so it can be done. I'm also a very conservative driver though.
 
The keeping it under 2k rpms helps a lot. I'm an aggressive driver and sit in mostly stop and go traffic on a 30 mile commute daily in my full time 4wd v8 with lift and 285s, best I can manage is around 13.5 avg.
 
The "lie o meter" is not a good gauge. You need to use the old fashioned method of fill it, set the trip meter to zero, drive it, fill it, and divide miles driven by gallons used. You will probably find that the trip computer is 1.5 - 2.5 MPG high.

Also I have not noticed any significant difference between AC on and AC off. Even if there was a difference if I lived in GA there's no way in hell I'd run without AC.

20 MPG is reasonable with a V8 if you are on relatively flat roads and moderate speeds. I have gotten 23 with my V6 under similar circumstances. Stop-and-go city driving, heavy acceleration or speeds above 65 will bring that down in a hurry though.
 
Interesting experiment, but I can't see the meager gas savings being worth no A/C in Georgia in the middle of the summer.
 
Hairris said:
The only source I have considered(accurate or not?) is the 4runner's trip computer in the center console. After driving about 500 miles in two weeks back and forth to work, my trip average MPG says 20.0!!!!!!
Click to expand...

It's not accurate. The next time you fill up, reset your trip odometer. Then after your second fill, divide gallons pumped by miles driven. You'll find that the trip computer is at least a couple mpg optimistic.
 
Here's my fuelly log for my 2007. I think the VVT-i engine might be slightly more efficient than the older ones. My average is around 18.
4runner (Toyota 4Runner) | Fuelly

There's a great list of tips on improving fuel economy on Ecomodder.
65+ Vehicle modifications for better fuel economy - EcoModder.com

Needless to say, the V8 4runner is a rare vehicle on the Ecomodder forums.

I suspect the spoiler is detrimental to MPG, especially if it's the scoop type that sticks up above the roof. But removing it leaves some holes to plug, and no 3rd brake light.

The roof rack crossbars are a pain to remove, but if you never use them it might be worth the trouble. Or you can remove the rails completely if you want, and plug the holes with a trim piece Toyota sells.

The side mirrors are huge drag flaps. I've considered folding my passenger side mirror in on long drives on single lane roads. Check the laws in your state before you try it.

I put in synthetic gear oil and 0W20 engine oil. I haven't seen any significant difference as a result, but small improvements should add up.

Increasing tire pressure seems to help significantly. You could reduce weight by taking out the seats if you never carry passengers.
 
I can appreciate you trying the experiment. But turning off the A/C in July here in the south is just not worth the gas savings.

I came to conclusion years ago that worrying about MPG is fruitless. Worrying about MPG makes the drive less enjoyable. We buy vehicles because we like them and want to enjoy them. It's just gas, it's meant to be combusted and expelled out the back of the car (or boat).

F&ck MPG and just enjoy yourself.
 
THX for the replies

Thanks for all the replies. It is interesting to see how many of you have quickly chimed in that the 4runner computer is practically worthless when it comes to accuracy. General frame of mind, maybe, but accurate, no!

For those of you who say the gas savings without AC is not worth it, I will tell you this. I am an Aviation Mechanic and work in a non Air-conditioned hangar all day with skylights that let sun in. It gets to around 85-90 daily in the hangar, even with a Big Ass fan going. SO.....A little drive with the windows down feel about the same.

A couple of you mentioned changing out the Gear Oil for Synthetic, or just change it all together. Did anyone notice any savings, or is this theoretical in effect as saying changing it out will allow all gears to move more freely than before, and as a result, better gas mileage?
 
My computer is almost dead accurate after installing a lift and 255/75/17 tires. It's reading 18.8 and last tank I averaged 18.6 hand calculated factoring the tire size difference.
 
Hairris said:
A couple of you mentioned changing out the Gear Oil for Synthetic, or just change it all together. Did anyone notice any savings, or is this theoretical in effect as saying changing it out will allow all gears to move more freely than before, and as a result, better gas mileage?
Click to expand...

I haven't noticed any savings. It's a small improvement, if anything, so it gets lost in the variance. If I drove the same route regularly I might be able to see it.
 
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