How can Ford list gas milage for 3.55 gears and 3.73 gears the same (14 and 19 MPG)? The 3.73 should not get the same milage as the 3.55. I like the FX4 with a 5.0L but can only get 3.73 gears. I do some highway driving and am afraid the millage will be quite a bit less than if I could get 3.55 gears. Does Ford put a higher 6th gear in the transmission in the FX4 to compensate for the lower rear ratio? That way you would still have the towing capacity but recope the millage on the highway????
Does anyone have any thoughts on this?

 

maybe the difference in fuel economy is so little, It doesn't change the numbers? I don't know, you do have a valid point though.

 

(maybe the difference in fuel economy is so little, It doesn't change the numbers? I don't know, you do have a valid point though.)


What that say is completly right the diffrence is so very little it dosent cange the numbers. On the other hand a 3.55 2wd gets 1 to 2 MPG better than the 3.73 4x4 But theres not a huge change in milage that 6 speed really helps fuel economy alot. The new 3.5L eco is the ticket i couldnt beleve how much more acceleration it had over the 5.0L If you havent drivven one you sould befor you buy the 5.0 and it gets better MPG than the 5.0l

 

It actually has to do with torque converter and wind resistance. Say going 70 with the 3.55, the engine doesn't actually have the torque to push the truck through the air with the torque convert locked up, so it will actually unlock so the engine can rev to the torque it needs without having to drop down out of overdrive. With the 3.73 gear, at 70 the engine would have the torque to push the truck down the road with the torque converter locked.

Peterson's Off-Road did an article about this when a Chevy Colorado driver noticed that his I5 actually got better mileage at 70 when he used direct drive instead of overdrive and wrote in asking why that was happening. All has to do with the torque available.

 

Okay. I have what you probably consider a dumb question. How do I know what the gear ratio is on my truck? Where is it listed, door panel?

 

Easiest way, call a Ford parts counter and give them the last (I believe it is this, have the whole number ready just incase) 10 digits of the VIN. They can tell you the axle, ratio, and differential type all from that. Only the assembly plants use the physical numbers tagged on the axles when axles sit around over night.

 

OP, the mileage listing in big numbers are the approximate mileage you can expect. The fine print under these numbers says you will probably get mileage within a range that's lower and higher. That does depend on the set-up of the truck, i.e. 4X4, 4X2, 3.73, 3.55 etc. It's all regulated by the government, and Ford plays the game just like the other auto makers.

For example my 3.7L Screw 4X2 w/3.73 gears mileage estimates are 17 city, 23 highway on the big numbers.. Actual city is between 14 mpg and 16 mpg. The highway mileage is between 21 mpg and 24 mpg depending on cruising speed. All within the estimate range in the fine print.

 

But 3/4 ton and up trucks do not play the game. And the keywords on the paper is, EPA Estaminet.

 

Look on the sticker on the door, it will say axle, then have a letter/number. For example my truck says B6, meaning i have a 3.73 limited slip.

These are the codes for F150s:
19 — 3.55 non-limited slip (F-150, Econoline)
17 — 3.31 non-limited slip (F150, Econoline)
H9 — 3.55 limited slip (F-150, F-250)
B6 — 3.73 limited slip (F-150, F-250)

 

Well that worked for my 02. Doesn't has an open diff with 3.55 though. Has a 3.55 with a locker...but that was my doing right there.