Assuming the trip computer for the new 2 mode Tahoe or Yukon is similar to our 2007 Denali. There should be data for total gallons consumed. This along with the odometer readings would provide a life of the vehicle average consumption.

FWIW, my "zero" mode hybrid , shows an average 15.9 MPG over ~30K miles.

I always reset my fuel consumed every tank, so it hasn't displayed lifetime consumption since my first fill up.

You can see my lifetime average consumption by viewing the database. I record total miles and actual gallons. I'm car 6478. Generally, the trip computer reads a little high compared to actual consumption.

Tom

So the actual gallons you measured is less than what the computer shows? I know that the average MPG seems to never be accurate (high & low). But I am a secondary driver so I am not sure when it is reset, other than when I do it.

No, actual gallons is more than what the computer shows. The display seems to show fewer gallons used than I actually put into the tank, making the calculated avg. FE high. I realize there are all kinds of errors introduced at each fill-up, and if I never reset, it might even out. I have not plotted or recorded the calculated vs. computer reading. (I went crazy doing this on the Prius).

Have you observed a consistent variation in computer versus fuel pump reported gallons? I plan to start monitoring the gallons per fill-up to see if there is a trend. As you stated each fill-up introduces all kinds of errors. But those should average out over multiple fill-ups.

FWIW, my daily driver's computer doesn't display gallons used. But the average MPG has been very consistent at +5% of actual (odometer/fuel pump) and over a range of 27 to 38 MPG (140K miles @ 9 yrs). Our Denali reports anywhere from -1.0 to +1.5 MPG. I use the computer to monitor "relative" MPG.

No, I've never recorded the computer vs fuel pump numbers to determine if there is any consistency in the Tahoe. You'll have to find someone more patient than me for that!