Connected Car, and Gas inaccuracies

Old May 12, 2019, 3:22 pm
  #1  
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Connected Car, and Gas inaccuracies

I had two rentals with Avis last week, apparently both being "connected cars" which meant that the fuel level was automatically recorded on return. Both rentals were off-airport pickup, airport returns.

The first rental I was charged ~$18 for gas, despite filling up the car about 4 miles from return. When I queried it, they stated that it was a "connected car", and the car had reported that it was not full. As I had driven less than 75 miles, they hit me with the basic "below 75 miles" fee due to me apparently not filling it up. When I pushed (and showed the receipt), they removed the charge.

The second rental was the more interesting one. When I picked up the car (Nissan Altima) the gauge was right on F, and it wasn't too far in that it started dropping below F so I was fairly sure that it wasn't full when I picked it up.
When I was filling it up a few miles from return I estimated that it should take about 1.3 gallons, including what was needed to get me to the drop-off (based on the MPG the car was reporting, and the distance driven). When it got to 1.52 gallons I stopped filling (ie, before it actually cut out). The gauge showed "F" just like when I picked it up.

When I returned, Avis's system decided I'd returned it with more gas than when I picked it up, and actually credited me a few dollars on the rental to cover! But the math just doesn't work...

According to the receipt, when I picked up the car it had 17.0 Gallons. On return, 17.8. So I put in 0.8 gallons more than I used. But I only put in 1.52 gallons, so apparently I used 0.72 gallons - to drive 48 miles.

So either I managed to get 67 MPG out of an Altima (almost double the 35 MPG it claimed), or there system really isn't as accurate as it should be...
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Old May 12, 2019, 4:13 pm
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Originally Posted by docbert
I had two rentals with Avis last week, apparently both being "connected cars" which meant that the fuel level was automatically recorded on return.
<snip>
Are "connected cars" actually measuring fuel tank volume/level or fuel flow/fuel used (over time)?
With the on board fuel electronic systems a transducer in the fuel line is probably measuring fuel flow/totaliser, as that is what gives you the mpg. As a guess they just analyse that data. Nothing to do with volume of fuel in the tank. There will be accumulated errors.
Given the odd shapes of modern fuel tank, measuring the actual fuel volume would be very hard.
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Old May 12, 2019, 7:42 pm
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Originally Posted by Mwenenzi
With the on board fuel electronic systems a transducer in the fuel line is probably measuring fuel flow/totaliser, as that is what gives you the mpg. As a guess they just analyse that data.
That handles the usage, but not the re-fill. How do they know how much gas (if any) you put into the car?
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Old May 12, 2019, 10:13 pm
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Unrelated to gas, I stop renting from Avis/Budget because some of their deceptive practices.

So I guess this is normal for Avis/Budget.
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Old May 13, 2019, 7:07 am
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If the car info is going to be used to charge for gas, then shouldn't the car be tested by the local/state inspector of weights and measures?
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Old May 13, 2019, 11:40 am
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I ran into this situation last year. Filled up tank to the brim; was charged $13.99 for fuel. This led me to read more into the connected car abilities. What's scarier is that Avis is constantly monitoring your GPS location while in an Onstar vehicle. I posted about this incident here: Avis Chevy Malibu incorrect fuel service charge

I look for Avis to get into a legal debacle at some point in regards to the "not being certified by weights and measures" thing. Sad thing is, they're still better than Hertz lol

TL,DR: I had GPS/"location services" turned off on my phone, yet when I was pulling into the rental car return area, the Avis app gave me a push notification saying "welcome back!". The only way they were able to get my location was through the car's GPS. On this same rental, I was charged $13.99 for fuel even though I had filled the tank to the brim.

Last edited by canyoncar; May 13, 2019 at 11:45 am
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Old May 14, 2019, 9:07 am
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Originally Posted by Mwenenzi
Are "connected cars" actually measuring fuel tank volume/level or fuel flow/fuel used (over time)?
AFAIK it's tank level, not volume consumed.
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Old May 19, 2019, 1:08 pm
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I rented a car and on the app it said that there was 12.7 gallons in the tank. I filled up right outside the airport and when I checked in, they had me at 12.9, so it seemed to work for me.

Do I get future credit for the .2 for being a good citizen if I turn it in a little light in the future?
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Old May 20, 2019, 5:31 am
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Originally Posted by sappstuf
Do I get future credit for the .2 for being a good citizen if I turn it in a little light in the future?
Are you saying you didn't get credit on this rental?

As I said above, I DID get a credit (at $4.11/g, which was actually more than I paid!), although that was 0.8 gallons difference, so perhaps the cut-off is somewhere between 0.2 and 0.8
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Old May 20, 2019, 8:32 am
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Originally Posted by docbert
Are you saying you didn't get credit on this rental?

As I said above, I DID get a credit (at $4.11/g, which was actually more than I paid!), although that was 0.8 gallons difference, so perhaps the cut-off is somewhere between 0.2 and 0.8
Nope. It is noted on my receipt that says I checked it out with 12.7 and back in with 12.9. There is a space where math would be done if I had turned it in with less, but it is all blank.
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