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Old 01-17-2020, 12:03 PM   #23 (permalink)
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Join Date: Apr 2012
Location: Evensville, TN
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Deep Blue - '94 GMC Suburban K2500 SLE
90 day: 23.75 mpg (US)

Griffin (T4R) - '99 Toyota 4Runner SR5
90 day: 25.43 mpg (US)
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I have read that as well on many forums, however I have not seen any A-B numbers to support the theory. Without lockout hubs, the only real effect would be having the front driveshaft not turn, which I wouldn't attribute to that sort to MPG gain/loss. Your CVs and some parts in the diff would still spin.

I believe people believe this based on the advertised MPG of new 2WDs over 4WDs and AWDs, which typically has more to do with weight and different gears than the turning resistance of the front driveshaft.

My wife's 3rd gen T4R has the multimode transfer case (2H, AWD, 4H, N, 4L) and there is no discernible difference from 2H to AWD on friction/coasting ability.
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