Ford Expedition MPG and Gear Ratios

mndadmndad Member Posts: 3
edited August 2014 in Ford
Heres the deal. My sister and I have the same truck. 2004 Eddie Bauer Expeditions. Both are 4x4 and both 5.4l. She followed us up north one weekend. We both used cruise control so we had identical driving situation. She only got 14.2mpg and I got 16.6mpg (actually calculating out the mileage) The only differance between the trucks is that I have 3.73 gears and she has had 3.31 installed several years ago. Do you think mileage will go up more on these with 4.10 gears?


  • tidestertidester Member Posts: 10,059
    That's interesting.

    Did you both use the same kind of gasoline? Do you both change your oil at regular intervals and use the same type? Are your tires inflated properly and identically? Did you both use air conditioning? Anyone have cargo racks? Use 4WD? Did the vehicles carry equal loads?

    tidester, host
    SUVs and Smart Shopper
  • mndadmndad Member Posts: 3
    I am a bit of a gear head. lol. I have experimented with different oils in nearly all of my vehicles in the past and have found no difference between using different types or brands. I did notice about a .1mpg increase using synthetic blended 5w20 over conventional 10w30 FWIW.
    Nearly everything else was identical.
    I have noticed that it doesnt matter if you drive 65mph or 85 mph. My mileage is always around 16.6 highway when I calculate it. My thinking is that getting the rpm up just 100-150rpms or so to increase engine torque is enough to compensate for increased wind resistance. I would also think that if the rate of acceleration was the same, but with 4.10 gears, the truck wouldnt have to work as hard, therefore decreasing the fuel consumption in city driving?

    I do know that the cylinder deactivation in the GM trucks are working better with the 4.10 gears vs the 3.73. The 4 cylinder mode engages more often and is able to hold that mode under more acceleration with the 4.10. The consensus is that the engine rpm is a little higher and producing more torque

    So I am wondering if anyone has actually done a 4.10 front and rear gear swap in their Expeditions and seen an increase in MPG. I have found front and rear gear sets for about $300
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