kjpilot
Full Access Member
Okay, so I had a chance to drive my 2003 KJ (with my new NP-242 T-case conversion) from Cincinnati to Minneapolis. It's a long dull drive of about 750 miles, so I thought I'd conduct another experiment on the AWD/2WD MPG controversy. As many know, I have shared the view that, contrary to popular myth, AWD (full-time, NOT part-time) will give you slightly better gas mileage than 2WD. To Quote myself the last time this case up:
"There are advantages to full-time AWD even on dry pavement. In 2wd, only 2 tires are suppling traction, while the other 2 are giving only drag (friction, resistance) in 4wd[full time], all wheels are productive members of the traction community. This results in slightly better gas mileage... Only slightly, because the 4wd drive train also gives additional drag, but not so much that it completely off-sets the traction advantage."
Well, I attracted some challengers with that statement. I shared the admittedly short test of this theory that I had performed in our 2001 WJ. I drove the same circuitous route of about 20 miles, once in 2wd once in full time 4wd in close succession. Using the overhead computer, the difference was about 1 MPG better in full-time 4wd.
If you do a search on this, you will see that I once said the route was 15 miles. I remeasured the route & it is indeed about 20 miles. But no matter! I have a new test!
I had the cruise set to 73.5 MPH (measured by GPS) I switched back & forth from 2WD to AWD every 20 miles. I did this to minimize the effects of changing wind, weather, & topography. Traffic also played a factor. Going more than 20 miles before having to slow down for construction, or running across slow cars in the passing lane is nearly impossible. I steered clear of the Chicago area traffic & tolls, by going through Bloomington, IL. & I ran into heavy traffic & severe storms from Rockford, IL up to La Crosse, WI, so those miles weren't tested. I also threw out any samples that were tainted by involuntary slow-downs, which are always followed by a voluntary speed-up. In all, I obtained ten 20 mile 2WD samples, and nine AWD samples... 200 miles 2wd, 180 AWD, 380 miles total.
Results:
2WD= 17.13 MPG
AWD= 17.36 MPG
Before anyone gets too excited... let me point out that if I had used Full-Time 4WD for the whole trip of 750 miles, I would have saved only 0.6 gallons over doing the whole trip in 2wd.
"There are advantages to full-time AWD even on dry pavement. In 2wd, only 2 tires are suppling traction, while the other 2 are giving only drag (friction, resistance) in 4wd[full time], all wheels are productive members of the traction community. This results in slightly better gas mileage... Only slightly, because the 4wd drive train also gives additional drag, but not so much that it completely off-sets the traction advantage."
Well, I attracted some challengers with that statement. I shared the admittedly short test of this theory that I had performed in our 2001 WJ. I drove the same circuitous route of about 20 miles, once in 2wd once in full time 4wd in close succession. Using the overhead computer, the difference was about 1 MPG better in full-time 4wd.
If you do a search on this, you will see that I once said the route was 15 miles. I remeasured the route & it is indeed about 20 miles. But no matter! I have a new test!
I had the cruise set to 73.5 MPH (measured by GPS) I switched back & forth from 2WD to AWD every 20 miles. I did this to minimize the effects of changing wind, weather, & topography. Traffic also played a factor. Going more than 20 miles before having to slow down for construction, or running across slow cars in the passing lane is nearly impossible. I steered clear of the Chicago area traffic & tolls, by going through Bloomington, IL. & I ran into heavy traffic & severe storms from Rockford, IL up to La Crosse, WI, so those miles weren't tested. I also threw out any samples that were tainted by involuntary slow-downs, which are always followed by a voluntary speed-up. In all, I obtained ten 20 mile 2WD samples, and nine AWD samples... 200 miles 2wd, 180 AWD, 380 miles total.
Results:
2WD= 17.13 MPG
AWD= 17.36 MPG
Before anyone gets too excited... let me point out that if I had used Full-Time 4WD for the whole trip of 750 miles, I would have saved only 0.6 gallons over doing the whole trip in 2wd.
