My daily commute runs about 9.5-12.5Mpg based on the overhead console, depending on the traffic. I've made the commute often enough that I have a good feeling of when it will be a 9/10/11/12Mpg ride. I've even comparison-checked my gut vs overhead by turning the display to temperature until I get to work.

The first half of my commute is generally about 2Mpg higher than overall (suburban -> urban). Today was a "9.5Mpg day" which generally has me at 12Mpg on the first half of the commute.

I've been playing with Tow/Haul on/off to see if locking out 5th would help and it really doesn't do much for me. I didn't expect to hit 5th, but I thought the shift point changes might help. Today I accidentally put it in O/D off, so I left it there.

The first half of the commute was 14.5Mpg and the overall was 12.5Mpg.

"More investigation needed."

 

Did you make any other changes besides hitting OD switch?

 

Nope. Normal driving style. If anything, I might have been a little more aggressive on the gas.

 

on my CTD I found that by using the tow/haul mode (no OD lockout for me) I get better mileage as well. ON my truck the TC locks up sooner and stays locked longer. Maybe yours is the same. In my sig I have a link to a mpg thread I started for tracking different setups and found the tow/haul mode gave better results.

 

Hrm. I wonder if I don't have enough RPM (and other conditions) in 4th to lockup the converter, but I do in direct.

 

mine locks early, (dont remember what speed or rpm) and in 2nd gear IIRC. it un-locks at 45 in OD when slowing down and will re-lock in 3rd when it downshifts... actually I think it will continue to lock all the way down to 2nd. It's been a while since I payed attention to how it locks & unlocks in tow/haul mode so I may be off a little here.

 

I tried to tell you guys this in another very recent post about "is running with tow/haul on bad" thread.

In my 04, my tow/haul is like your OD off. My truck will not shift into OD when I have it on. Ive said many times throughout numerous posts, I run with my tow/haul on everytime no matter where Im at, and how fast Im driving. I see consistently, a 2-3 MPG in town improvement. The way these trucks are geared, there shouldnt even be an overdrive in these trannys.

BTW. What do you guys run at 70 MPH, OD off, with 4.56 gears? I guess I could just calculate it.. lol

 

With standard 33" tall 275/60R20 and 4.56 gears would be 3250rpm @ 70mph

 

This morning was 13.6Mpg. I've never hit 13Mpg before on the commute.

 

Rojhan, what gears you got? .......and 5 dogs? Whut! I couldn't deal with 1. They are like having children.