This was an unscientific MPG study on my new 05. My truck is mechanically stock, stock 215 tires as well. My additions are the GM hard, folding bed cover and a Lund bug shield.The truck has just over 3200 miles. I have done hand calcs comparing those with the DIC and those hand calcs are within + or - 0.1 of the DIC. I trust my DIC.

On a flat section of interstate highway, 77 degrees air temp, unloaded, me and one passenger I got the following mileage.

56 mph...21.3 mpg
61 mph...19.6 mpg
66 mph...18.2 mpg...2000 rpm indicated on the tach
71 mph...15.3 mpg...big drop off from 66 mph

I was using Power Service Diesel Kleen additive when I recorded the above information.

Without Diesel Kleen I got 16.7 mpg at 66 mph on the same section on interstate, not loaded, same passenger, air temp was 75 on that day. 66 mph was the only speed I recorded mpg for w/o any fuel additives.

Compared to my 2000, K3500 crew cab, 7.4 liter gas, SRW my new truck gets outstanding mileage. At 65 mph my MPG was just under 9 mpg in my old truck.

I also watch the MPG closely on my DIC. The only time I hand calculated actual was about .5 mpg lower than DIC indication. I've seen a lot of people complaining about mileage. I know if I keep mine right at 65 (I know, hard to do) I get right at or just above 18 DIC. Actually got 19 at one point. Mileage is EXTREMELY dependent on RPM and thus speed.

I also watch the MPG closely on my DIC. The only time I hand calculated actual was about .5 mpg lower than DIC indication. I've seen a lot of people complaining about mileage. I know if I keep mine right at 65 (I know, hard to do) I get right at or just above 18 DIC. Actually got 19 at one point. Mileage is EXTREMELY dependent on RPM and thus speed.

My DIC is alway 1 mpg bigger than when I do it manually. Said another way, I'm not getting what my DIC is telling me I'm getting by 1.

Ed

the day after i bought mine we drove from ohio to gatlinburg .running 70 to 75 mph my dic said 19 mpgs when we got home i hooked up my 21 foot toy hauler and went to campton ky and got 14 towing at 70 to 75 mph

I just got back from a vacation in the hill country , which is in the south Texas region. Going last Thursday I kept the cruise on 70-73. Which is a little slow considering I was literally getting blown off the road by EVERYONE else. Scenic drive lots off up and and downs and I hand calculated 15.3. Coming back today I had a powerstroke blow by me just after we left the hotel and I couldn't take it. I ended up running 75-90 almost the whole way.I told the wife we were on a hard fuel run and I pushed my dually pretty hard. Coning back into Dallas I stopped for a top off and milage check and guess what 14.65. Screw babying it, for now on I'm gonna drive it like I want to and I'm just not gonna worry about the milage and enjoy my truck.

LOL...Thats the spirit... I will be pulling my 33 ft toy hauler (Labor Day)..loaded to the gills... from Phoenix to Strawberry Az. This will be my first pull with this truck so I will let you all know how it does... I'm bone stock with a stack seal and 19000 miles on it. I'll be facing the dreaded "25 mile hill". I will be following a buddie in his Powerstroke and another with his Cummins..(or should I say, I'll be leading).... I'm sure the competition might get a little rough...but I'll do my best..If I can't post milage...I'll at least let you know who won.;)

Maybe it will get better later ?

My truck has 7300 miles and the mod's listed below !!
On a trip Friday night on pretty flat land I got the following :

80 mph = 21 mpg
70mph= 22 mpg
60mph = 25 mpg

Around town mine is getting worse it seems like : 14-15 mpg.......where it was 15-16 a few weeks ago and I was getting on it more !! Anyway , I think the hwy milage is real good.......it beats my 5.3 Z-71 for sure !!

Maybe it will get better later ?

My truck has 7300 miles and the mod's listed below !!
On a trip Friday night on pretty flat land I got the following :

80 mph = 21 mpg
70mph= 22 mpg
60mph = 25 mpg

Around town mine is getting worse it seems like : 14-15 mpg.......where it was 15-16 a few weeks ago and I was getting on it more !! Anyway , I think the hwy milage is real good.......it beats my 5.3 Z-71 for sure !!

Are those DIC readings. If so, I see you are running a programmer so they wouldn't be accurate. Don't think I've ever seen someone with an LLY post #'s that high.

Yeh , That's off of the DIC with the program loaded !! Maybe it is wrong........I dunna know.........but it "definately" is getting much better milage than my Z-71 !! Do programmers really throw the DIC's off much ???

Yeh , That's off of the DIC with the program loaded !! Maybe it is wrong........I dunna know.........but it "definately" is getting much better milage than my Z-71 !! Do programmers really throw the DIC's off much ???

Yea sure do.
Mine is showing an average of 22.3 mpg (and I know thats no where near right. I run the preditor for now, and thats what causes my discrepency.
On the other hand, I just got home from a trip from Atlanta to Destin. Going down, unloaded, I hand calculated 20.508 mpg. :ro) This is my all time best- sure beats my old 6 liter GMC. I normally run around 15-18 mpg. I also just turned around 11,000 miles.

04.5 lly Just got back from vacation and was in a hurry to get home for some reason. But anways we went 80mph(about 2600rpms) the whole way home and averaged 18.3mpg. And that was with the edge/attitude on stage 5 the entire trip.

My previous trip I used the chip on stage 3 and got almost identical fuel mileage.

Mines only turning about 2100 @ 80 .........sound about right to anyone ?

Thanks for the info. on the programmers changing DIC's........didn't know that but I will hand calculate to see what I'm actually getting !!

I think 2100rpms sounds about right at 80mph with 285's, but with stock 245's it is usually around 25-2600. If this isn't what others are experiencing please let me know.

Mines only turning about 2100 @ 80 .........sound about right to anyone ?

Thanks for the info. on the programmers changing DIC's........didn't know that but I will hand calculate to see what I'm actually getting !!

The DIC is ruined for mileage calcs once a tuner or box is installed. The bigger the tune the worse the error.

.

Hey Stallion , whatever you do DON'T let the other 2 out pull or out run you and if you have to lie about the milage we all will back you up. If all else fails just remind them you are in a CHEVY.