Cascadias with dd13 and dd15 mpg

I know the automatics with the DD15 is getting anywheres from 7.0-8.0 mpg. I know because my 2019 gets that. I'm not taking the truck over 70mph though.

 

The last dd15 I was in had the 505 and dt12 with 2.64 rears. With 45k on it and not even broke in it was avg 8.2 doing multiple stop food service

 

Its a good fuel efficient truck. The automatic is a little scary in the bad weather but its a good truck.

 

Are you guys running full locking diffs ?

I don't need mine often, but when I do I am very thankful for them..

 

We were limited to 62@1375 rpm. You won't ever see above 7.2 if your running 70+ all the time. I found 1375 to be the sweet spot on the dd15. The older trucks we had 2.47 rears and they did 0.75 mpg less than the newer

 

What difference does that make? Just wondering.

 

Have heard it takes more energy to turn all of that. Extra weight. Also why some companies have been trying the drive axle just turning the forward axle and the rear is just a tag axle. Fuel economy, so they say.

I wouldn't have a truck without full lockers though. I view it as the price of 1 hook = defeated entire purpose.

 

I used to get 7 at 70 mph. I changed out the michillins to Yokohama now 6.6.

 

I could see that. I dont think it adds a whole lot of weight. I have full lockers in my '18 Cascadia, and did 6.67 mpg 3rd quarter of this year. Plus I have a ton of idle time because I have to pump all the products I haul with either air or hydraulics.

The guy I work for has a '16 Cascadia with a dead axle, DT12, DD15, did 8.xx 3rd quarter