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MPG gauge in HV mode Accuracy

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We have a 2022 RAV 4 Prime SE in which the last few months I have been keeping track of the HV mpg gauge with a depleted battery. ( I know the battery is not completely depleted but this is when the computer starts the gas engine). The method I use is when the battery is depleted the gas engine kicks in and I then reset the mpg gauge to reflect 0.0 MPG.

The last few trips the gauge MPG averaged out to 52 -53 MPG. Note: Difficult to get it 100% accurate as each trip, a total of 6 in HV mode, ranged from 40 miles to 114 miles. I filled up with 350.7 HV miles on this tank with a total of 6 trips. The gas used is Costco 87 regular with 10% ethanol. The method used was the lowest setting on the handle and when it auto clicks off remove the nozzle from the filler tank. This is the method I have been using for consistency.

With 350.7 mlles the tank took 6.800 gallons 51.57 mpg. I noticed that our Prime's mpg gauge is more accurate than our 2010 prius was. With the prius it was consistently off by 3-4 MPG. For instance a dash gauge reading of 55 mpg would be calculated of 51-52 MPG.

Just checking to see if any other owners have had similar results with their Prime.
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We have a 2022 RAV 4 Prime SE in which the last few months I have been keeping track of the HV mpg gauge with a depleted battery. ( I know the battery is not completely depleted but this is when the computer starts the gas engine). The method I use is when the battery is depleted the gas engine kicks in and I then reset the mpg gauge to reflect 0.0 MPG.

The last few trips the gauge MPG averaged out to 52 -53 MPG. Note: Difficult to get it 100% accurate as each trip, a total of 6 in HV mode, ranged from 40 miles to 114 miles. I filled up with 350.7 HV miles on this tank with a total of 6 trips. The gas used is Costco 87 regular with 10% ethanol. The method used was the lowest setting on the handle and when it auto clicks off remove the nozzle from the filler tank. This is the method I have been using for consistency.

With 350.7 mlles the tank took 6.800 gallons 51.57 mpg. I noticed that our Prime's mpg gauge is more accurate than our 2010 prius was. With the prius it was consistently off by 3-4 MPG. For instance a dash gauge reading of 55 mpg would be calculated of 51-52 MPG.

Just checking to see if any other owners have had similar results with their Prime.
I’ve never gotten ICE mileage that high. Average for my frequent 110 mile, 35-60 mph ICE trips, some stops, very light traffic is 42 mpg. At 75 mph interstate my HV mileage is 35 mpg.
To check your methodology, suggest you estimate how far you can travel, typically, on a “full” traction battery. For me that’s 42 miles. Fill up both the gas and traction battery. Take your trip(s), use up your EV capacity, measure the total mileage, subtract 42 (or whatever) EV miles, and divide by gallons used. I’ll take a wild guess it will be lower than 52 mpg, but take the test and see.
 

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Discussion Starter · #3 ·
We live in Northwest Oregon on the Pacific Coast. Speeds ranged from 25-45 MPH in town to a 55 MPH speed limit on the main highway here which is Highway 101, along with Highway 30 and 26. I have noticed that when I go through town my mpg will pickup from 46-48 mpg to near 50 mpg driving at low speeds.

Our electric range this summer has been 45-55 miles on a full charge. My next test will be to run the battery until the gas engine fires up. Than go to the gas station, Costco, . fill up and drive for 100 miles or so without charging and fill up at the same station and pump with the same method. This should give me a more accurate reading of the mpg dash gauge compared to calculated mpg.

I have noticed when going down a mountain pass in HV mode (depleted battery) just south of us here on Highway 101 we will gain 3 miles of electric range and the gauge will switch from mpg to miles per KWH. We can then drive for quite a while on electric and the gauge will switch back to mpg with a considerable gain in mpg from when it switched. This entire amount of electricity was gained by regeneration from the decline in elevation.
 

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High MPG numbers are pretty easy when you work in sample sizes.
If you only drive a short distance at a set speed, the sample size is too small to be overly reliable.

If I am understanding correctly, OP drive 350 miles on gas, but over what span? Is that 2 miles a time over the course of 4 months? You're basically telling us what your MPG is in 2 mile increments (or whatever it is that you are resetting the 'meter' at.
Yes, it truly is 50 mpg but it isn't like saying you took a 360 mile trip on all gas and achieved 50 mpg.


And resetting it when the motor comes on sounds exhausting.
 

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Discussion Starter · #5 ·
On that tank there were 6 fishing trips beginning with a full battery that ranged from 90 miles to 160 mile round trips. The average of those 6 trips, based on 350.7 miles divide by 6 = 58.45 HV miles. In total since I have been tracking HV miles the last few months have been:

Total HV miles: 1,756.7 ( all calculated with a depleted battery when the engine fires up by computer)
gas pumped (Costco reg. 87 octane): 34.227 gals.
MPG 51.573
 

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BTW, Using a couple of GPS aps, at an indicated 72 MPH on the dash, the GPS aps are indicated 70 MPH. Generally car companies calibrate the speedos to be bit optimisitic. So it the car is using the indicated speed calculating the MPG its going to be higher than actual.
 
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