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Discussion Starter #1
facts/given:

2015 RAV4 AWD Limited, OEM tires, est. 85%/15% highway/city driving; most of the highway miles are mountain roads between the Antelope Valley and the Pasadena area, as a commute, (usually the two-lane road over the mountain, occasionally, around the mountain on the very congested freeway when the mountain road is closed due to ice/snow/rock slides). Include several multi-day trips from SoCal to north Idaho - rarely exceeding the maximum posted speed limit as well as a handful of day trips to the Owens Valley/Yosemite/Sequoia for recreation opportunities. Overwhelmingly fill up with Costco 89 octane.

Started keeping and recording fill-ups on October 14, 2015 when the odometer registered 1,089 miles.
Latest fill-up was yesterday, January 28, 2017 when the odometer registered 39,653 miles.

I have been saving all my receipts for the past 38,564 miles. Upon each receipt, I record the odometer reading, the trip odometer, and the mpg as calculated by the car, (in five cases, I did not register some of the data, but except for the car-calculated mpg; the odometer and trip odometer readings are easily interpolated from adjacent receipts).

1.) 157 fill-ups of an average of 9.489 gallons per each fill-up
1a.) The least fill-up was only 3.171 gallons, (topping off at the beginning of a trip to Oregon)
1b.) The maximum fill-up was 14.003 gallons.
2.) The car calculated the mpg to be an average of 26.888 mpg
3.) The spreadsheet calculated the average mpg to be 25.885 mpg

Observations:

a.) The overall difference between what the car displays as the average mpg is about 1 mpg greater than the actual consumption.

b.) However, from tank-to-tank, it is highly variable. The difference between what the car displayed and actual range from between +2.4 mpg and -5.1 mpg.

c.) Only pattern I can discern is that the lesser the amount of gasoline purchased, the more inaccurate the car mpg reading is . . . but not always!

d.) All-day trips with minimal stops tend to not only give the highest mpg, (duh!), but also the most accurate car-calculated readings . . . but again, not always!

Conclusion:

The car-calculated mpg output is a "toy". It's fun and interesting, but not to be relied upon when determining where and when to obtain your next fill-up. With a maximum gasoline capacity of 15.9 gallons, if I were a fool, I should be able to drive 411.6 miles before I have to start walking.

But who wants to walk? On the highway, I think a reasonable maximum range between fill-ups would be 350 miles, (13.5 gallons at 26 mpg), and in the city, about 300 miles, (13.5 gallons at 22 mpg). On the highway, that's over five hours at 65 mph. The seats in the RAV aren't that comfortable and we'll have to get out to stretch anyway.

Just wanted to pass on my observations about how my RAVs doing. And, how I learned how much I can trust the car calculated mpg readings.
 

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I use a phone app called Gas Tracker by Fuelly to keep track of my actual mileage and I have found that the car calculator is always 1 to 2 mpg off. With Gas Tracker it stores the information on their website and combines it with other people who have the same vehicle so you can go to that site and see what type of mileage that people are actually getting.

With my 2015 XLE AWD, with 130 fill ups logged, my best is 31.7 and my overall average is 25.6 mpg.
 

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Same here - great app and easy to input data. You can do it right after you fill up! See my signature for the mileage so far.

Car's a year old today!!! Happy Birthday! Have put 29,000km on it.


I use a phone app called Gas Tracker by Fuelly to keep track of my actual mileage and I have found that the car calculator is always 1 to 2 mpg off. With Gas Tracker it stores the information on their website and combines it with other people who have the same vehicle so you can go to that site and see what type of mileage that people are actually getting.

With my 2015 XLE AWD, with 130 fill ups logged, my best is 31.7 and my overall average is 25.6 mpg.
 
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