W900L and T800

My guess is same mileage. Those t800 have a slanted hood but usually sit up much higher so more turbulence under the truck than the 900.

 

The 800 isn’t a very aerodynamic truck.probaly be close to the same as the w9, seems crazy trading a w9 for a 800 tho..

 

Minimal difference.

Keep the nice truck if you like it.

If you really want fuel savings be very very very light on the pedal.

 

T8 would turn a lot shorter if they are a similar wheel base, but I doubt you would gain on milage going to a 10 speed not being able to split gears if the rear ends are the same ratios. One of my friends has 2 T8's with paccar's and 10 speeds and averages around 7mpg though according to the dash on the truck.

 

My old man has a t8 with a 12.7 3:55 13 speed I have a 379 B model cat 3:90 15 speed. 3/10 difference in mileage. I drove the t8 for a while pulling flat and my 379 does mid 6's just like the t8 did.

 

Currently drive a 2009 isx 425 t800 3.9 reat and a ten speed. Grossing average of 70k i can average 6.5 easily. Upwards of 7.5 with lower weight, and a lighter foot.

 

I have a t800 72” flat top glider. Detroit sr 60 18 speed...... love that truck .... mid 6’s to low 7’s pulling drop deck. Sold a t600 studio with a cat that averaged low 7’s driven nice & easy..... now I have to stomp the Detroit to get down the road but I don’t mind the drop in mileage.
The t8 seems to cut sharper, can fit anywhere just about. It does ride up a little higher off the ground but it’s just that much easier for grease & oil. Couldn’t give me a w9. Pretty trucks but I’ll take my snub nose any day. So anyhow mileage w9 to t8, not worth it in my opinion. W9 to t6, now it might pay off. T8 = best of both worlds to this cracker head