joepajamas said:
I have been looking at getting a newer truck. I would like to have this truck for the next 10 years or so. With fuel prices the way they are I would like the darn thing to actually get 20mpg freeway. The trucks I have been looking at are shortbed extended cab models in the 2500HD series. Will these actually get 20mpg. If I spend $25k and the dam thing gets 16mpg I am going to be pissed because then I would have been better off just buying a gas motor. I really like the solid front axel, and the way the 6 speed shifts and feels, it seems to be at 1600rpm-1700rpm on the freeway at 65mph, which seems like it would yield good mileage. With the six speed, one might be able to put on larger tires without changing ring and pinions.
I thought about some of the 2000-2002 models, but after driving the newer generation cummins, it seems the quieter motor might be nice.
Does the 2003-2007 third gen cummins motor yield the best mileage of the 5.9 series?
Any thoughts on this matter appreciated.
Basically,the newer the Ram,the worse the mileage will be. The 1st gen 12valves get the best. The second gen 12valves,then second gen 24 valves. Finally the 3rd gen 24valves. The reason the 3rd gen is in last place is because of the way fuel is injected. The early 3rd gen have 3 injection events,and newer have 5 injection events. Having more injection events makes the Cummins mucho quieter,but less fuel effiecient.
Going to bigger tires will also kill some fuel mileage. Yes bigger tires will decrease the RPMS some,but bigger tires have more rolling resistance. Aggresive tires also have more rolling resistance. The 3rd gen Rams can easily fit 33s stock. 35s with a 2" front leveling kit. 37s with a 4" lift and 38s or more with a 6" lift. My brothers Z-71 needed 6" of lift to fit 35s.
The Rams don't have super strong front ends though.. They have enough problems with ball joints,wheel bearings,etc going out without adding big tires. I want 35s in the worst way,but between towing a fifth wheel and wearing out the front suspension quicker I'll stick with 285s (33s).
My '07 5.9 4x4 with the 6spd manual gets about 19mpg at 60,18 at 65,and 17 at 70. Much past 70 and the mpg goes in the crapper really quick. Thats hand calculated and factoring in the taller tires.
If you want 20mpg,I'd find a 2003-2004 with a manual tranny,go easy on the big aggressive tires,and you MIGHT average 20 on the freeway.
Finally,you won't get 20mpg with a gas engine,unless its a 1/2 ton with a small block engine. A 3/4 ton with a small block (6.0 Vortec,5.4 Triton,or 5.7 Hemi) WILL not get you 20. You probably won't even average 15-16.