What are the implications of "No MPG Sensor"?

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On the car compatibility page for my 2001 Honda Insight, it says "This car doesn’t have an MPG sensor. Mileage will be calculated using your car’s EPA estimate." But I've seen some other community posts that discuss other sensors (like "Mass Air Flow") being used to calculate the value. I've seen variable has mileage in my trips so far, so I assume it's using more than the EPA estimate. So I have two questions:

1. Why doesn't the car compatibility page mention the more nuanced calculation?
2. How is the fuel economy actually calculated for my car specifically?

Thanks,
Josh
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Joshua Fishburn

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Posted 4 years ago

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Tom, Former Employee

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Thanks for your question, Joshua. Tech support is looking into your account, and I'll post again when we have an update for you.
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Tom, Former Employee

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Thanks for your patience Joshua. I heard back from our tech support team, and I have an update for you. It looks like the app is calculating the fuel economy of your car by reading data from the manifold absolute pressure (MAP) sensor. This data is then analyzed along with a special coefficient for your car in order to determine your MPG. So why is the app using MAP sensor data? Since you car doesn't have an MPG sensor or provide Mass Air Flow data via the OBD-II port, MAP is the "next in line" for determining MPG. If, in turn, your car didn't provide MAP sensor data, the app would then uses the EPA estimate to determine MPG. As explained in this topic, the EPA rating displayed in the app can change from trip to trip as it's based on the percentage of time you spend driving on the highway and on city driving.

Sorry about the incorrect message on the car compatibility page. Our team is still investigating this and whether there could be variability in how we determine MPG for 2001 Honda Insights. Thanks also for your feedback on how we should include more nuanced information regarding MPG calculation on the compatibility page. I'm going to pass this along!
(Edited)
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Joe White

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This reply was created from a merged topic originally titled The 2014 Ford Fusion shows "supported", but what about MPG?.

The 2014 Ford Fusion Hybrid clearly operates with miles/gallon information when I drive it.  Why does Automatic indicate that this model does NOT have MPG sensor?

Is the problem related to further development work that Automatic needs to do to support this capability on Ford?
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Tom, Former Employee

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Hi Joe! I merged your question into a related discussion on the implications of not having an MPG sensor.

This is a really good question. Some cars will report miles to empty and miles per gallon in their own dashboard but do not make that available through the OBD port. It is either not provided at all or is transmitted in a manner that we can't interpret.

So how then does Automatic determine MPG? If your car doesn't have an MPG sensor, the app then looks for Mass Air Flow data (via the OBD-II port). If that’s not available, Manifold Absolute Pressure data (MAP) is "next in line" for determining MPG. Finally, if your car doesn't provide MAP sensor data, the app then uses the EPA estimate to determine MPG. As explained in this topic, the EPA rating displayed in the app can change from trip to trip as it's based on the percentage of time you spend driving on the highway and on city driving.
(Edited)
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reverik

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I am also using the Automatic with a 2014 Ford Fusion Hybrid. The automatic is reporting MPG for me and does not appear to be estimating it based on EPA. Does that mean it is using the MAP sensor? Can we get confirmation? How accurate is the MAP sensor?
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Tom, Former Employee

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Hi reverik. Sorry for the delay in getting back to you. Can you send a message to tech support about this? I'm unable to locate your Automatic account, and for privacy reasons, we ask that you write in instead of posting the email address tied to your Automatic account here in the community. You can reach tech support at help@automatic.com. Thanks!
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Joe White

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I guess I should clarify my question -- I am asking specifically about the 2014 Ford Fusion Hybrid and whether MPG information is supported using the "Automatic" device -- not a general statement.  I need this specific information to determine whether to purchase.
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Tom, Former Employee

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Thanks for the clarification, Joe. Yes, Automatic will be able to calculate MPG information for your specific vehicle. I had tech support check how we determine MPG for the 2014 Ford Fusion Hybrid, and it looks like we use MAF data for a majority of them. Keep in mind, however, that how we determine MPG can vary from submodel-to-submodel.

Reverik, this answer also applies to you, but if you want 100% confirmation that we're using MAF with your vehicle, be sure write in to tech support.

Sorry for the confusion regarding the EPA message that you both saw in the car compatibility database. We've identified a discrepancy that will be addressed. One of our compatibility tables had not been updated, and we're working to resolve it.

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