Well I've gone through a few tanks of gas in 4WD and 2WD and I can confidently say that switching to 4WD doesn't affect gas mileage dramatically. If you have a 4WD equipped V6 and you drive in 2WD, the gas savings if any are not significant. Since you have to lug around the extra weight of the 4WD components whether you are using them or not. I would guess that the drive train loss being in 4WD isn't too much either.

Now if you are a 2WD only vehicle, the lighter weight should give you better gas mileage.

See my signature for my gas mileage in Excel. Feel free to comment and if someone can check my formulas to verify my calculations that would be kewl.

Oh yeah, if you've got nothing positive to contribute and you want to spew off something like "eh its a truck live with it" please refrain.

Note: My daily commute takes me through I95 through the DC Metro area and through the Springfield "Mixing Bowl". It's a lot of stop and go driving.

Sharp - your numbers look good... Nice work putting together and maintaining a spreadsheet like that... Mine is a bunch of gas receipts with mileage in the stash beneath the console lid.... My average is a little higher since I have more highway speeds and backcountry roads (no traffic) and no hood scoop :-)

I have seen roughly the same effect, maybe as much as 1 MPG lost in 4WD, but nothing appreciable. I see a bigger loss from warming up the car for 10 minutes (tried this a few times) than driving in 4WD.

thanks for the compliments. I wish I could say that I have all the receipts but invariably some got lost or someone drove the truck and filled it up without getting a reciept and mileage.

My commute sucks. I am only like 17 miles from work, but it usually takes me 30-45 minutes to get into work. They've been doing construction through my route for years and it doesn't look like it isn't going to let up anytime soon.

Makes complete sence, it's the weight of the 4x4 components that leads to lower gas mileage, the only significant numbers I've seen where on 2wd trucks verse a 4x4.

Are you gonna run premium and see if it effects your mileage

I ran premium for a while and it didn't make a differnece. See the column that says Grade. P means premium in the spreadsheet.

Makes complete sense.

The drivetrain drag of 4wd is always there. It is irrelevant whether you engage 4wd or not because the road engages all four wheels and essentially "drives" the front axle and all it's 4wd components anyways.

A 2wd only truck save gas not only because of weight, but because the front end drivetrain is not there to cause drag through the front wheels.

Hope the people who complain about the V8's not having selectable 2wd/4wd can finally understand this and get over it.

About the only real "advantage" of the selectable 2wd is the lighter cornering feel.

I've got a 1998 v6 4x4 and I reguarly get 19/21 in the city. If I don't push it too fast, I might break 23 on the highway. The best gas mileage I've ever gotten was 25+ when the truck was engaged in 4wd. Might have something to do with running it < 45mph during that tank, not sure.

May I also add that there isn't a real big difference in mpg w/ the 4 spd vs the 5 spd tranny. They both get about the same mpg or perhaps the 5 spd may gander 1-1.5 more mpgs per gallon. One would think the new 4th gen 5 spd tranny would be at least 15-20% more fuel efficient.

Unfortunately, Toyota pawned off the 3rd gen 4 spd tranny in my 2004 V6 4X4. I get the same consistent, combined overall (17 mpg) whether driving in 4 wheel or 2 wheel drive. That's about all one is going to get out of these setups.

TeCKis300, I agree about the lighter cornering feel while in 2wd mode. That's one of the things that eventually made me choose a V6.

I disagree about whether it changes drivetrain drag if you're in 2wd mode vs. 4wd mode. In 2wd mode a vacuum(?) actuator disconnects the front axles from the differential, and the transfer case disconnects the front propeller shaft. Drivetrain losses really do seem a little lower, and the difference is maybe 1 MPG. Probably less than 1 MPG at lower speeds and a little more at higher speeds. Not a big deal if you have a specific engine preference.

Great job in documenting your travels! I don't know too many people who would do such a thing. I tend to keep it logged in memory but it doesn't last long!!! LOL! It appears you haven't used 4WD as much and I'm concerned your data may be skewed. It only shows 4 times with 4WD giving you your best mpg at 17.566 where as with 2WD you peeked at 19.374 mpg back in August last year. You consistantly remained above 17 mpg all around and spent quite a bit of miles in this range. Although the extra weight may play a factor, it looks like 2WD is the way to go. Wouldn't you agree?

Have to agree with Mica.

Don't have the spreadsheets to back it up but going by the trip computer (and compared to sharp, I have a longer commute with much less traffic) been able to achieve an indicated 22.5mpg (-10% = 20mpg). Once we start to use the 4WD more regularly it doesn't take long to affect the indicated reading negatively.

Happy to read this since I am possibly looking to buy a 4WD for my son.

I also did research on the 4Runner before I bought mine, it took less than 5 minutes to convince me that this was the truck to have. I had a 1997 Grand Cherokee with 4.0 I-6 and got 13.8mpg. With my 2005 V6 runner, i consistantly get 21mpg. On the highway (doing 60mph), I've seen 25mpg. I once saw 28 (then again, it was traveling from a town 1700ft in elevation to 500ft ). Good luck with your decision!

why is the v6 changeable from 2wd to 4wd, but the v8 is only 4wd all the time?

anyone know?

I did a similar study in my 2008 4WD earlier this year. I ran alternate tanks in 2WD and 4WD for a total of about 8000 miles. I found a .25 mpg difference. My miles are almost entirely city streets or urban freeway where its impossible to maintain a steady speed like you could on an interstate. If you assume 12,000 miles per year and $3.00/gal gas, that's $31/yr difference.

Is there any long term disadvantage to running 4WD all the time from a component wear standpoint?