CACalomino

Well I found two trucks im looking at one auto one manual I have driven both but I want to know witch will get better mileage on the highway. My 05 in my sig got 18-18.5 at 65 all day long. I know the G56 has lower gearing and run's higher RPM's but will it get better mileage compared to the same truck with 3.73's or 4.10's and a auto. The truck would be a QC 4X4. The dealer also has two 05 2500 2wd's with the G56 they have not sold for some reason wonder what kind of milage that would get over the 4WD

-Thanks for any feedback I realy apreciate it

-Chris

v8440

I have an '05 2500 6 speed. One of my buddies has an '06 2500 auto, both having 3.73's, both built on the same month. Mine kills his on in town mileage because I don't go around slipping a torque converter at low speeds. His highway mileage is better by about 2 mpg.

IA_James

If I'm not mistaken, the OD ratio is actually a little bit higher on the automatics. If you spend alot of time on the highway, with the tq. converter locked up, it will do better than the 6 speed as far as mileage. Towing and around town the 6 speed will do better.

Edit: I see you are talking about the G56 vs. NV5600 manuals, the G56 with 3.73's will be about like an nv5600 with 4.10's, and the associated mileage penalty.

SSminnow

2WD DRW here, NV5600 3.73's @ 70MPH @ 2000 RPM give or take a few RPM's, 235/80-17 tire = 17-17.5 MPG


IF I drop it to 65 MPH it will run 18-19 MPG all day long on the highway.


I have made quite a few road trips to verify mileage, both at the speeds mentioned above, and those are hand calculated. I have yet to have ALL in town driving mileage, since I end up on the highway at one point or another through out a tank of fuel

v8440

My comparison was two '06's, which means 48re and g56. If you're wondering about mileage around town with a 2wd g56, my 2500 CONSISTENTLY gets over 21 mpg in the city, hand calculated. BUT, I drive specifically for mileage. As in, I coast long distances up to traffic lights, shut the engine off at long lights, and I shift at 1250 rpm under normal circumstances. You can get away with shifting at that rpm unloaded because the gears are so close together in the g56.

Raspy

The very slight difference in RPM caused by the OD ratios in the auto and the G56 will not mean a thing in over all mileage. The difference is the automatic is generating more heat and must maintain oil pressure all the time, so it's less efficient. Even in lockup it has oil pressure and more waste heat.

Wetspirit

Nav

06 QC 4x4 DRW G56 3.73 rear unloaded averaged 16.5 in mostly rural type driving.
On Highway at 70 (2300rpm) averages between 15.5 - 16 consistantly.
This is averaged over 7500 miles, hand calculated each time.

With 10k Fifth wheel in tow, rural is 11.5 mpg, highway at 65 is 9.5-10mpg
Based on 1500 miles towing

These are just some real world numbers. Maybe someone with the same setup and auto can post their numbers. Remember, 4x4 will be worse then 4x2 and DRW will be worse than SRW.

Nav

CACalomino

All good info. Well I Like the G-56 and driving a manual but I drive 90% highway and if the maunual gets worse than the auto I might have to go with a slush box over rowing bliss. But I guess I could always put 35's on the manual and drop some Rpms's hmmmmmmmm wonder if that would help on the highway.

Keep the feed back coming guys

-Chris

Nav

Part of the mileage difference is that the G56 comes with the 3.73 rear but since the G56 is internally geared lower the net result is equal to the Auto running a 4:10 rear. The old NV5600 was geared higher so it used to get better mileage.

Nav

sweetwaterguy

I am one of the lucky ones who seem to get great mileage. In January I completed a 2400 mile round trip, Wyoming to Yuma, AZ. My hand calculated mileage was 20.4, slightly better than what was indicated on the overhead computer. I drove in a variety of conditions, keeping the speed limit (65) and did not exceed 70 on interstate highways.
I live two miles from town, and with 250 miles since the last fill, my mileage reading on the overhead is 19.4. 100 miles were highway. The rest was to and from town. I have a 04.5 with a six speed. It is my understanding the manual transmissions are more efficient than auto's. Don't have any data to prove that, though.

xyzer

48RE here....16.5 town 20.5 on a 500 mile round trip hand calc. 3000 total miles so far. When I first got it 13.5 was the best I could get....got a CEL and they reflashed it and mucho better!

D.Wiggs

My 22.5" wheels with 255/70 Sumitomo traction tires (36.9" overall height) on a completely stock height truck (no rubbing) will be installed next week and I will be able to give you some real world numbers with the new gear ratio (3.19 instead of 3.73). It means that you can cruise at 75 with the RPMS of 65!!! Should be a nice hike in MPG!

SSminnow

Not to hurt your feelings here, but the bigger rubber will add to more friction and more rolling resistance, which of course leads to worse fuel economy. Now, since the tires will be taller, and your revolutions will be less per mile, you would see an increase in fuel economy IF the tires weighed the same/produced the same amount of resistance. So, any increase you would see, will be offset by the weight/rolling resistance of the tire, sorry You may see a LITTLE increase in fuel economy, but do not expect any dramatic difference.

Nitro71455

I had 33's on mine, and lost 1.5 mpg.... off they went and the stockers back on....Milage is back to normal now

06 48re City Coasting and turning engine off at light with very light accel from light to light and from any stops is 16.5 to 17.5

Highway at 75 is 18.5.... I drive fast on the freeway and haven't checked at lower speeds yet though I know I'd pick up at least 1 or 2 mpg at 65.

RAMRODD

I'm looking forward to hearing your results. which I expect to be + by 2-3 mpg. Even if the mpg stays the same, I would think it would be worth the fact that your engine won't have to be screaming to drive drive the speed limit.