[millsrv]

We have had the RAV4 Hybrid for one week now and filled it up yesterday for the first time, as it was filled by the dealer new. The cars calculator said 30.4 MPG and our math after fill up was 30.3 MPG.
After watching many YouTube videos on the hybrid RAV we had expected the actual mileage to be lower than the cars estimate. Not the case on the first tank.
Please let us know how your Hybrid is doing on this subject.

We took a 100 mile road trip yesterday through the Sierra Nevada Foothills and the car says 33.9 MPG at this point. We hope that is also accurate. Time will tell.

 

[erapmicks]

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[rdgrimes]

We have had the RAV4 Hybrid for one week now and filled it up yesterday for the first time, as it was filled by the dealer new. The cars calculator said 30.4 MPG and our math after fill up was 30.3 MPG.
After watching many YouTube videos on the hybrid RAV we had expected the actual mileage to be lower than the cars estimate. Not the case on the first tank.
Please let us know how your Hybrid is doing on this subject.

We took a 100 mile road trip yesterday through the Sierra Nevada Foothills and the car says 33.9 MPG at this point. We hope that is also accurate. Time will tell.

Single point measurements are rarely reliable due to the many variables. Over time and multiple tanks you will get an accurate picture of what its doing. That said, I find the car's computed average MPG to be pretty reliable and usually not more than 1MPG optimistic. Again, based on multiple tanks.

 

[garyd9]

If you click the Fuelly link below this message, you'll see that I recorded (in the "notes" section) the car claimed MPG for several of the fill-ups I've done. As you can see, there's an obvious difference. In some cases, the car reported a higher mileage, and in other cases a lower mileage. It's usually off by around 2MPG, but in one case it was off by as much as 5 MPG.

HOWEVER, that difference might be more related to fuel pump shutoff points being different than any inaccuracies in the car computer. My "typical" fill-up pattern is to fill the tank until the pump shuts itself off, wait 5 seconds, and then top it off again (once.) However, if the pump auto shutoff is more sensitive, it'll put less gas into the tank, which will result in a higher reported mileage for that tank.

This is why accurate mileage can only be determined by averaging over the course of SEVERAL fill-ups (without special equipment.) I wouldn't even trust using the "same pump at the same station every time" method... the pump's auto-shutoff could be influenced by humidity, temperature, etc.

So, as to how accurate the car's computer is for actual MPG... it seems, on average, to be within 1-2 MPG of the average reported by tracking by hand.

 

[Oli77]

I can't tell yet, I have had zero fillups ?.

In my bmw it is off by 1 mpg every time (computer thinks it is a more fuel efficient car than it really is).

 

[tom555]

My fuelly record also lists the car's computer (ECU) estimated mileage in the notes section,

RAV4h (Toyota RAV4) | Fuelly

There is also a forum thread on this topic at fuelly. My car is systematically optimistic about mileage, but not by a fixed offset.

Car's computer agree with fuelly? - Fuelly Forums

 

[rdgrimes]

True, the difference might be a percentage offset, so the faster your average speed the more difference there will be.

 

[tom555]

As described in my fuelly entry on this subject, the actual mileage vs car-computer mileage is described pretty well by this expression:

(actual mileage in MPG) = 0.76 x (mileage reported by computer) + 6.8

Note that the actual and car-computer mileages are equal at 28.3 MPG. As mileage increases, the car-computer estimate becomes increasingly optimistic.

---

For those who enjoy data, here is what the relationship looks like:

https://docs.google.com/spreadsheets/d/1ebH7InLcN5gQ9TwSHHbtHstF0VKakznc2Ex3sdQftyI/pubchart?oid=1845134874&format=image

 

[Oli77]

I think in that fuelly thread somebody hit the nail on the head. The computer probably does a running average or a weighted average on mpg from a series of instantaneous calculations. You know those when it just puts down a number like 99 mpg, because you're foot is off the gas. In the end, and every time, those calculations are over-inflated.

 

[vetterin]

My actual mileage is consistently 2%-3% lower than stated.

 

[RichXKU]

My actual mileage is about 0.96 * [displayedMileage]

 

[tom555]

After a recent road trip, the comparisons of actual vs. car computer mileage becomes more confusing.
Tank 1: actual = 31.6 car computer = 32.5
Tank 2: actual = 33.1 car computer = 33.0
Tank 3: actual = 36.5 car computer = 36.6

So it seems there are some situations where my car computer is quite consistent with the calculated value (Odometer readings/# gallons at the pump). Mysterious. More study needed.

Also confusing, but admittedly a new topic, is that the first tank of a road trip earns an anomalously low mpg, while subsequent tanks do much better. This is the second time this has happened. Even more mysterious...

 

[Oli77]

First tank actual: 37.2 mpg; computer 38.0 mpg, close to RichXKU 0.96 factor (except its .98). Pretty darn close!

 

[Sliderul]

I just took an 815 mile road trip of which 650 miles was freeway and much of that at 80 mph. I checked against the computer at every fill up and this is the second time I've done so over the 5,000 miles I've put on the car. I've found the computer to sometimes overstate mpg and sometimes understates. When most of my driving is stop and go the computer tells me 34 - 36 mpg and I find that to be overstated by 1 or 2 mpg. When driving at freeway speed for extended drives, the computer says ~ 30 mpg and that is understated by 1 - 2 mpg. For my full 815 mile trip, the computer was very close to actual.

 

[mkz168]

I must be one of those few crazy drivers to only gets around 28mpg...


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