Gas milage of 2wd vs engaged 4x4?

[Boosted131]

I'm wondering what the difference in fuel economy would be for a full tank if it was driven in rwd or 4x4 the full time. Anyone know the percentage difference?

I know awd vehicles lose like 10-15 percent.

[Mibz]

Depends on the vehicle, obviously. On my Cherokee I'd notice a drop from ~450km/tank to ~400km/tank but you also need to factor in the that it's winter and you're likely spending more time idling and in stop/go traffic.

[FraserB]

The ONLY way you will see a difference is if you can engage and disengage the hubs in the front. If it is simply disconnected at the transfer case, the entire front end is still spinning and you see no difference.

The Cherokee is like that for sure, the Dakota probbaly is as well.

So the short answer is no savings or a savings so small you will never notice it.

[b_t]

in my Tacoma 100% highway driving turning off 4WD improved mileage by maybe 5%. Totally not worth it imo.

[ercchry]

there is for sure more load while engaged... i have a dead lift pump and can cruise at 120km/h in 2wd no problem... in 4? 90.... so painful

[r3ccOs]

I don't know about you guys... but if I do shift into 4Hi (not auto awd engaging or AWD viscus couplings/Haldex etc..)

from RWD in any truck, I find it looses probably closer to 30% in fuel economy...
bolds true with my friends TJ

[r3ccOs]

Originally posted by FraserB
The ONLY way you will see a difference is if you can engage and disengage the hubs in the front. If it is simply disconnected at the transfer case, the entire front end is still spinning and you see no difference.

The Cherokee is like that for sure, the Dakota probbaly is as well.

So the short answer is no savings or a savings so small you will never notice it.

even if the front axel is spinning, its not recieving power distribution from the transfer case and is not the same as being locked to the same speed as the rear axel

[benyl]

I don't know if my F150 disengages the hubs or not, but I can definitely feel the extra drag when 4Hi is angaged.

With Blizzaks DMZ1s and a rear locker, I hardly have to use 4Hi.

[Boosted131]

I drove to work today without using the 4wd at all, if it's not much of a difference I wouldn't mind it though. Rear diff auto locker sure works nicely though On this truck

[Kramerica]

Depends on the vehicle, common number I've heard thrown around is 0-15%, I'd probably lean closer to zero.

Remember you're vehicle is still the same weight and requires the same amount of power to move, the mechanical inefficencies you save by not sending power to the front is just offset by the extra power set to the back and lost through there. Add to that the fact that you're now stressing the rear diff with that extra power and it becomes worthless to do in my opinion. The money you save in gas mileage will be offset by having to change the rear diff fluid more often. Better thing to do is keep a 2wd car and a 4x4 winter beater.

[msommers]

Yeah the rear fluid definitely gets a lot dirtier than the front if you use 2wd a lot more. I find mine fuel mileage drops off but really, I could care less about the few bucks in gas that the benefits of driving with 4wd bring.

That said, I do that just in the winter months. Rolling around with 4wd engaged on pavement probably isn't the best idea unless it's full-time.

[CapnCrunch]

Originally posted by Boosted131
I drove to work today without using the 4wd at all, if it's not much of a difference I wouldn't mind it though. Rear diff auto locker sure works nicely though On this truck

Buys 4X4 truck, avoids using it at all costs.

[Boosted131]

Haha I just wanted to try out the auto locker and it worked good. Already played with the 4x4 enough offroad

[r3ccOs]

Originally posted by Boosted131
Haha I just wanted to try out the auto locker and it worked good. Already played with the 4x4 enough offroad

I don't effing get truck driver mentalities.....

With no weight over the rear axel, mud terrain tires, a higher center of gravity , and especially 3/4 and full tons with solid front axels, they fair WORSE on a icy highway than a FWD let alone a AWD car would with the proper tires

yet these hillbillys think their trucks are so much more exceptional in these hazardous driving conditions, tailgating everyone and ripping around well beyond the speed limit

My neighbor is the type, takes his truck up to Horizon every 15 days and for some reason is always in a hurry...
I borrowed it one snowy day last year, and you "HAD" to drive it in 4HI all the time, because you couldn't in just RWD with his 38" Mudders

and I quote... my good year MT/Rs are the best snow tires I've used! I can keep 150 on the QE2 for hours on the worst ice!

[msommers]

That's the typical oil patch worker mentality and it's a headache to try to explain how it doesn't make sense. The higher, louder and wider your truck, the bigger man you are apparently. From what I've observed, most of the guys in office-type positions out here don't have hugely modified trucks, it's the more labour intensive positions that I see owning them. Again just an observation.

I was actually making fun of one of the guys out here after asking me about winter tires. He's so fucking cheap to buy winter tires yet he spent $600 per frigging tire to get these mud tires for his 20" rims.

[Boosted131]

I have general grabber at2 . 31 inch and they have the snow flake rating. They do good in winter for sure.

[r3ccOs]

Originally posted by Boosted131
I have general grabber at2 . 31 inch and they have the snow flake rating. They do good in winter for sure.

I used those in the past too... awesome tire, better than BFG AT for winter roads

BFG a bit better for deep mud or deep snow

also for truck tires, the Cooper ST-C was very good to me as well (studded)

none as good as a true winter like a Nokian, but will do just well on a SUV

much better than a mud terrain on a empty box half ton

what I love best is setting those retards with the Interco Super Swampers rolling around in the Winter

a tip that works well for ME for lightweight 4x4 vehicles...
deflate your tires on those really icy cold days
though tire pressure does drop as temps do, often times people are running minimum C ply, let alone E ply tires on a truck that isn't carrying the weight... i.e. Jeep TJ's which really are about the same weight as a car

just air it down to give you the sidewall flex and more contact patch

Car's are different, they rely more on the sidewall bite, and their sidewalls aren't designed to carry 2000lbs per tire

[jsn]

Originally posted by Boosted131
I have general grabber at2 . 31 inch and they have the snow flake rating. They do good in winter for sure.

That's what I'm rocking too right now. Worked pretty good last winter out on the highway and lease roads.

[..*JDM Hatch*..]

I use an 08 F150 as my winter beater, 4Hi kills my milage in the city,due to stop and go conditions and it engaging all the time. But i run 33'' Nitto Trail Grappler MT's on my truck. Dont really have to use 4x4 very much. Unless it's spring break-up and your leaving the rig.

[BerserkerCatSplat]

Originally posted by r3ccOs


even if the front axel is spinning, its not recieving power distribution from the transfer case and is not the same as being locked to the same speed as the rear axel

Power distributed to the front axle is taken away from the rear, for a net zero change. Fraser is correct, to eliminate the drag from the front assembly, the diff must be made independent from the wheels to remove the power loss incurred by spinning the assembly.