I a looking at a WS 5700 with DD15 and DT 12 AUTO

Have not had my 2 very long but they made it off the dealers lot with no problems , not automatics but getting decent performance out of them ride good and nicely laid out inside. Talked to someone who has 3 automatics and he is very pleased with the fuel mileage he is getting.

 

DD16 , 13 speeds with 3:23 ratio 22.5 LP tires 70" sleeper

 

spec that with 2.64s and direct drive with 505hp. We run the northeast doing food service, a lot of the time overweight and fleet avg for the dt12 is low 7s. Personally I've been in one that was 8.1mpg and these are ryder fleet spec trucks. Our 10 speeds with 2.47s are lucky to hit 6. 100 truck fleet about 30 autos.

I don't like autos but as far as im concerned the dt12 is rock solid, light years ahead of the pos eaton autos

 

were limited to 62mph and small rubber with 2.64 is 1370 at 62. If your running flat land go for 2.47s or 2.42

 

Everything on the 5700 is the same as the 4900 and the 4700 and the 6900 with the exception of the bumper, hood, sleeper and skirts. mechanical reliability is not going to be any different than the freightliners or other WS models are running.

I am looking at one with the dd16, 18 speed and 3.55 to 3.70 rears, might go as low as 3.55. Probably keep the gross weight at 105,500 or less up to about 130k. I drive mostly in states with 65 mph speed limits so the gearing should be fine but still get me over the passes.

I know of one guy here running a 4900ex with the dd15 and a 13 speed pulling a grain hopper at 105,500 and is averaging over 7 mpg.

Oh wait! That's not possible, it's not an aero truck.....

 

I'm still breaking mine in. I've put about 4k miles on her so can't really comment on MPG. She rides as quite at 60'as she does 80. Had no power at all for the first 2000 miles but that is common with the Dd15. Not much I can say or add at this time.