How inaccurate is the MPG on the cluster?

[Gatorlac]

So the first trip I took in my Esky I was getting 18.5 MPG, the next trip with my Airaid installed I got 19.2....not bad at all I was happy with that. Then last week my gfs car was idling a little rough so I bought TB & MAF cleaner and decided I'd clean mine up as well. Took a 3 hour trip this past weekend and reset my MPG to see if I got any improvement and I'm getting unbelievable mileage now!!!

75-80mph @ 2200 rpm 22.2 MPG
65-70mph @2000 rpm 23.3 MPG
55mph @1900 rpm 24.5 MPG

I am not complaining LOL even if its 2 miles off that's still more than I ever expected, cant wait to see what I get with a BB tune! I'm getting 16.5-16.8 in the city but I'm sure I can get another 1-2 miles once I get the hang of driving this thing, Ive had it for a while but its hard to get the coasting down because it decelerates SOOOO slowly almost like the cruise is set between 25-40. If I set my cruise in that range I can hear my truck hit the gas for a split second then let off for a few seconds lol...is that normal???

 

[humer101]

I think that depend on how you drive, city drive and (idle) that will kill everything.

 

[Gatorlac]

obviously how you drive and how long you idle will effect it a lot but I'm talking strictly hwy driving here. Im just wondering how accurate/inaccurate the MPG calculator really is... I even had the A/C running most the time and still got those numbers, that's better than what I was getting in my northstar!!! smaller V8 and a little bit lighter although Id assume its the same technology used to calculate mileage...

 

[coolchuck]

Dont know how much its off but I'm cleaning my throttle body this weekend. Those are amazing numbers. Even just a little increase helps.

 

[JochenWoern]

I calcualted the old fashion way and my number from the DIC in the cluster was off by 2 miles per gallon.

I do not believe it to be very accurate.

 

[yates ™]

I have seen fairly accurate and a little off, ask on the same vehicles. I use them strictly for guesstimation and hand calculate from time to time.

 

[Moose912]

I have never checked the DIC to see what it shows... I usually reset my trip every tank and do the math (total miles divided by gallons pumped.) My 05 Denali XL is getting around 15, on a damn good week. Is your truck a 5.3 or a 6.0? My 04 Z71 hoe got those kinds of numbers, sure do miss them ha. I am going to have to do a TB cleaning and some intake work to get my numbers up... Just need some time!