3.73 vs 4.10 mpg

redwngr · January 26, 2020

14 hours ago, i82much said:

maybe he needed the 8’ bed and extended cab? do they make that in a 1500?

1500 extended (now the double cab) is only available with the standard bed.

8' on a 1500 only available with the reg cab truck

L86 All Terrain · January 27, 2020

My 18 6.0L is a pig on gas at 65mph+, if you baby it and don't mind being the slow guy on the road, loafing around 1750-1800rpm they are surprisingly efficient. But put a load on or rev up to 2,000+ to get 65-70mph kiss your economy good bye.

A 3.73 in OD (0.67) on 31" tires would net you 1,760rpm at 65mph

A 4.10 in OD (0.67) on 31" tires would net you 1,935rpm at 65mph.

You're talking 1-2mpg. Take a long time to pay off that gear swap in fuel savings. Your best option is to trade it on a 1500 if the 2500 is not necessity and more of a want. They will never be able to match a 5.3L or even a 6.2L in terms of economy. But seeing you have a 8' bed you probably need it. I get around 10-12mpg with my CCLB 6.0L that always carries 125gal of diesel on board.

curver900 · January 30, 2020

you won't make up the gas cost via mileage difference if you trade it in.. you will take just as big a bath on the trade in... Worrying about mileage on a truck is like worrying about the weather... if it is mileage you seek a small efficient car is what you should buy....

The biggest cost of a vehicle especially trucks is the depreciation... gas/diesel is like number 3 on the list...

combining insurance and gas over 5 years is less than the depreciation...

Ownership Cost

Ownership Cost for 2018 GMC Sierra 3500HD (Denali Crew Cab 4WD)

Estimated: $66,201 over the next 5 years

Cost of Ownership

Total: $66,201

Depreciation ($24,430)
Insurance ($12,539)
Fuel ($11,953)
Maintenance ($8,207)
Repairs ($3,752)
Taxes & Fees ($5,319)

SierraHD17 · February 2, 2020

Fuel economy on these pigs is relative to aerodynamics, rolling mass and weight. When I got my 2017 HD it was a 3.73 geared extended cab std box 4x4. My drive home from the dealer on the stock tires I averaged just shy of 18.5 mpg on a 400 mile drive. I figured it was a fluke with a tail wind or something but was able to stay in the 16 mpg range fairly easily and even better. I then of course leveled the truck and added a 295/60/20 tire to the mix and the mpg dropped to 13 or 14 mpg. I never liked the performance of the truck even stock so I dropped in 4.56 gears and now can see 14 mpg pretty easily and even 15 mpg at times. This is of course running around the 65 mph mark as any faster and it's down around 12 or 13 mpg. I almost would like to stick stock tires back on and drop the trucks front back to stock height and see what my mpg would be... I don't think it would be drastically different.

i82much · February 2, 2020

Also keep in mind - weight plays a bigger factor in stop-and-go driving, aerodynamics becomes a bigger issue at high speeds. So, for instance, a lifted truck will probably see a bigger hit at highway speeds than a stock height truck with an intact air dam.

cmysstailights · February 2, 2020

Fuel economy on these pigs is relative to aerodynamics, rolling mass and weight. When I got my 2017 HD it was a 3.73 geared extended cab std box 4x4. My drive home from the dealer on the stock tires I averaged just shy of 18.5 mpg on a 400 mile drive. I figured it was a fluke with a tail wind or something but was able to stay in the 16 mpg range fairly easily and even better. I then of course leveled the truck and added a 295/60/20 tire to the mix and the mpg dropped to 13 or 14 mpg. I never liked the performance of the truck even stock so I dropped in 4.56 gears and now can see 14 mpg pretty easily and even 15 mpg at times. This is of course running around the 65 mph mark as any faster and it's down around 12 or 13 mpg. I almost would like to stick stock tires back on and drop the trucks front back to stock height and see what my mpg would be... I don't think it would be drastically different.

What did it cost.you for the gear change

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