2006 Tahoe MPG gauge question

My girlfriend drives an '06 Tahoe. On the dash display, you can flip through a few different things and eventually it'll show you the average MPG.
My question is, how is this measured? My 2000 Saab has the same thing,
but I can reset it at will, and then it'll figure MPG from the last reset. So far, I haven't figured out a way to reset it on the Tahoe. So from which point it's determining MPG?? Since new? Since the last startup? Since the last fill up? Since the last reset of the trip meter?
Overall, I don't really like the computer in that thing. The "driving range" view is very strange, as it'll drop while you're driving faster than you can cover the distance. This is at 55mph with the cruise control set. It'll lose 2-3 miles of range over the course of a mile, then finally settle down. OR...it'll remain constant and then when you park, right before shutting it off, it'll drop dramatically.
Kinda wish GM would incorporate some of Saab's stuff into their Chevy/GMC trucks. The onboard computer leaves much to be desired.
Oh yeah, the cruise control is weird too (compared to the Saab). It's not smooth. You can feel it "jump" a bit when engaging or disengaging, and it'll try to "floor it" going uphill, causing high revs and a downshift. I've had to drive it recently while the Saab is getting worked on at the dealer...
Thoughts?
~jp
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Since the last reset

Idle is the last thing it sees, idle is zero miles per gallon

Do you think the fact the Tahoe weighs about three times as much as the Saab might have anything at all to do with that?
Dont get me wrong here, I drove one of the very first Sabb 900 Turbos, with an intercooler back in the mid 70's while stationed in Germany, damn thing was fast. Also ugly as sin, and the electrical systems, back then at least all the way through the mid 90's(last i worked on one) were night mares.

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Whitelightning wrote:

Reset of what? The tripmeter?

Agreed...but this isn't a consistent thing. And that thing doesn't react too quickly. Nowhere near as quick as those numbers are changing.

LOL... Well, not really. I've driven equally heavy vehicles that handled cruise control with a lot more finesse. There also seems to be a delayed reaction when you turn it on. Worse, you can feel it "engage" while setting it. In the Saab, you hit the button, and you don't realize anything happened--until you remove your foot from the gas and the car doesn't lose speed.

The turbo sure does make it a lot more fun, doesn't it?? :-)
I've only owned mine for about 2 months now (9-3 convertible, turbo, 5sp) but I'm loving it.
~jp
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I am trying to remember how I reset the MPG in the last rental car I had, a Ponitac Grand Prix. It should be in the owners manual though. The range resets every time you fil the tank up, based on fuel mileage. so if the vehicle was driven hard during the last fuel up, the range will be less than if its driven easy, but that updates as well based on mpg. I found the readings were pretty close during the week I had the Grand Prix. Doesnt sound like very long, but I average 43,000 miles a year.

I have found in the past when the rule was no replacement for displacement, the cruise was smoother on all vehicles. They may advertise 200 hp (just using numbers here) from these smaller displacment engines, but my seat of the pants tells me its not the same as the 200 hp I was used to feeling in larger engines, coupled I think with the fact the torque band isnt as wide, and not nearly as flat, meaning a big time curve in the center. I do think the the cruise system will drop a tranny gear too soon sometimes, but I also think thats because its trying to keep the engine from lugging. At 70mph that GP was loping at just over 1600 rpm, it didnt take much of a grade to cause it to drop and then it kicked down and rpm jumped to about 2,000 if it just unlocked the torque converter, 2,300 if it droped all the way to drive.

didnt have a speed limits except in cities. : )
Whitelightning
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Whitelightning wrote:

After getting really frustrated I sat in the parking deck after work for 10 minutes and found it... You can reset it directly by hitting the bottom-right "arrow" button on the steering wheel. Simple enough, but not very clearly marked. I didn't find it in the manual, although I'm sure it must be in there. As soon as you reset it, it "zeroes" out and starts tallying MPG from that point on--same as my Saab.

Well, the Tahoe doesn't drop a gear unless it tries to go up a hill, then it guns it and downshifts. I futzed with the cruise again on the way home to make sure I wasn't imagining anything. While holding a steady 55mph on level ground, I engaged it. It pulled the pedal out from underneath the foot and surged for a split second, then took over. Annoying...but then again, it's not my truck, and the woman thinks it's just great, and as long as she likes it, cool... In the meantime I await the return of my Saab, as the dealer couldn't fool with it today.
Damn, I wish my K5 was in town (and had a good rear axle) :-(

Heh...now that's my idea of fun.
~jp
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