September Gas Mileage

[shatto]

September Gas Mileage

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This is for "Clyde The Ride" my 2006 4.7 5spd-auto Tundra SR5 TRD

Start:
23373 miles, 9-3-2008
23729, 9-5 $75.37, 20.376 gal @ 3.699 17.5 MPG.
23883, 9-8 $32.84, 08.925 gal @ 3.679 17.3 MPG.
24085, 9-9 $43.28, 11.765 gal @ 3.679 17.2 MPG.
4428, 9-11 $72.03, 19.580 gal @ 3.679 17.5 MPG.
4746, 9-13 $67.82, 18.435 gal @ 3.679 17.2 MPG.
5084, 9-16 $68.50, 18.671 gal @ 3.669 18.1 MPG.
5275, 9-18 $40.36, 11.214 gal @ 3.599 17.0 MPG.
5503, 9-19 $45.55, 12.657 gal @ 3.599 18.0 MPG.
5740, 9-22 $49.49, 13.827 gal @ 3.579 17.1 MPG.
6119, 9-24 $81.63, 21.949 gal @ 3.719 17.3 MPG.
6457, 9-25 $70.50, 19.320 gal @ 3.649 17.5 MPG.
6554, 9-26 $20.89, 05.838 gal @ 3.579 16.6 MPG.
6775, 9-27 $44.17, 12.412 gal @ 3.559 17.8 MPG.
7107, 9-30 $64.11, 18.063 gal @ 3.549 18.4 MPG.
7493, 9-30 $68.57, 19.825 gal @ 3.459 19.5 MPG.
7583, 10-01 $17.99, 05.083 gal @ 3.539 17.7 MPG.

4210 Miles - $863.10 - 17.61 MPG.

The 19.5 MPG was between Sea Level and 7,382 ft.
The trip was from home base in Concord to San Francisco then up Hwy 80 passing Donner Summit at 7227 ft to North Lake Tahoe, then out through South Lake Tahoe and down Hwy 50 to Folsom, where I gassed up, through Sacramento and down hwy 80 to 680 and across the Benecia Bridge and home.
I set the cruise control at 67 MPH and let er run. As you know, sometimes they get a bit fanatic about keeping the speed, so it was not uncommon to see the tach at 3,200 RPM's.....

Which leads to the question;
Why was my best mileage going uphill at over 1,000 RPM more than I usually drive at?

Also, you can see why something that gives me as little as one mile per gallon more is of great interest.

[theholycow]

Setup a garage entry for your Tundra and feed that data into the gaslog. It will graph everything and make it more easily accessible.

Your uphill observation is probably a result of one of these things:

- The climb wasn't enough of the 19.5mpg tank to destroy a particularly good tank

- Pump error -- each pump shuts off at a different level of "full".

- Your engine responds well to high elevation, with its low air pressure and such

- Forced P&G with DFCO -- if you went down the mountain in that trip, you have just practiced a huge pulse followed by a long glide with no fuel running to your engine. The engine produces work more efficiently when it's more heavily loaded, and the climb demands much more work; but then, when descending, if your RPM was over 1000 the fuel may have been off the entire time.

It could also be any combination of the above.

[Snax]

I am actually able to get 2-3 mpg better efficiency out of our 5 with mild hills even without DFCO or EOC'ing. Just taking it out of gear on the descent makes the difference.

[shatto]

What is strange is that my recently departed Dakota did exactly the same thing on the same run.