Normal Mpg's?

Mazer18 · December 16, 2010

Recently I have only been able to get between 10.5 to 12.5 mpg according to the DIC. Right now it sits at 10.8.

My truck is a 2007 GMT900 RCLB, 4.8, 3.42 1500 Silverado. Major mods so far include a RC level, Blackbear tune, and new tires recently (285/70/17 Duratracs).

I do a majority of my driving in town; probably about 75%. However, even whenever I hit the highway I don't see my mpg increase much even if I reset the DIC before jumping on the highway. It seems like my mpg stay constant regardless of my driving. A year ago I can recall the DIC reading 13ish in town and maybe 17 on the highway.

Would you say this is to be expected with the mods I have and to get over thinking about mpgs with a truck? Or is there something behind this?

Pic of said truck

landmine · December 16, 2010

That seems really low to me, but I have an 04 ECSB 5.3 with 3.73s. I get about 13 around town and 17 to 18 highway. My guess would be the tires. I wouldn't think it would hurt mileage that bad tho. I did lose about 1 to 2 when I went to my A/Ts. They are 265/70/16 so I think you have other problems, but I don't know much about the 900s.

jdewolfe · December 16, 2010

That seems really low to me, but I have an 04 ECSB 5.3 with 3.73s. I get about 13 around town and 17 to 18 highway. My guess would be the tires. I wouldn't think it would hurt mileage that bad tho. I did lose about 1 to 2 when I went to my A/Ts. They are 265/70/16 so I think you have other problems, but I don't know much about the 900s.

Yeah definitely does seem low. I have been getting about 12mpg with mine in town, but that has been with warming it up in the mornings and screwing around in the snow. Highway I'll get close to 20 with her. In town I normally get about 14.

jro909 · December 16, 2010

for one the dic is not accurate as far as mpg...two your running bigger size tires then stock let alone knobbys which will for one throw your speedo/shifts off but also your dic's calculations...overall i like your truck though i have a sweet spot in my heart for RCLBs

Stevens03 · December 16, 2010

Is the bigger tire size programmed into the tune?!? If not, you need to have that updated and your mileage will report correctly.

sliderbkt · December 16, 2010

What tire pressure are you using. I had the same tires on my old truck and mileage varied a bunch with the pressure. I went from 32psi to 45 and my mileage went up. Plus the ride was actually better.

dewfpo · December 16, 2010

Do you have a remote start? Warm it up much? Both of those things kill mpg numbers as well.

DEWFPO

terzmo · December 17, 2010

Recently I have only been able to get between 10.5 to 12.5 mpg according to the DIC. Right now it sits at 10.8.

My truck is a 2007 GMT900 RCLB, 4.8, 3.42 1500 Silverado. Major mods so far include a RC level, Blackbear tune, and new tires recently (285/70/17 Duratracs).

I do a majority of my driving in town; probably about 75%. However, even whenever I hit the highway I don't see my mpg increase much even if I reset the DIC before jumping on the highway. It seems like my mpg stay constant regardless of my driving. A year ago I can recall the DIC reading 13ish in town and maybe 17 on the highway.

Would you say this is to be expected with the mods I have and to get over thinking about mpgs with a truck? Or is there something behind this?

Pic of said truck

5.3/308/6 speed......bit over 18 around town...drops when using auto 4 wheel drive but still around 15 on that...no DIC to compute...just fill and do the math

Mazer18 · December 18, 2010

Thanks for the help so far fellas!

To answer the questions:

No, I do not have the new tires programmed into the tune. I plan to soon tough.

I am currently running I believe 36 psi in these tires. Come to think of it, when I had 40 in them I do believe I got better mileage. They are expensive tires though and I want them to last. I had no luck doing a "chalk test" but the tracks look OK in the snow. Did you have decent wear at 45psi?

No remote start, but I do give it a minute or two to warm up in the mornings.

kmborland · December 19, 2010

thats really low for being tuned with only 285. my dads 04 crew cab 4x4 with 285 get in the high teens around town and in the 20s on the highway. ur getting hat i am getting with my 95 tbi 4x4 truck except i get better highway than u (16mpg)

sliderbkt · December 19, 2010

I sold the trcuk that I had them on after about 13,000mi. But at that point they were wearing very even.

mudpuppy · December 21, 2010

I have an 06 ECSB Z71 with 3.42s and 285 BFG All Terains at 40 PSI. I've got a 5.3 and a BlackBear tune and I get 13 mpg city and 15 hwy at 65mph. Thats manually calculating it, not using the DIC.