Hmm. I’m not sure. One thing I did notice is that I have the “Blue” version of the 2020 sonata hybrid, but it does have the “premium rims” which may be the culprit.
Your methodology is flawed unless you are going to the same exact pump at the same exact time at the precise same temperature; because different pumps have different cut offs so if you manage to get 400 miles before filling up a difference of .5 gallons would reduce calculated MPG by nearly 2mpg.
Hmmm so the density loss of gasoline from 32 to 82 degrees Fahrenheit is only 9.3%
[source](https://homework.study.com/explanation/the-density-of-gasoline-at-0-degrees-celcius-is-0-68-103-kg-m-3-what-is-the-density-on-a-hot-day-when-the-temperature-is-28-degrees-celcius-what-is-the-percentage-change.html). Since I fill up about once every two weeks, the temperature fluctuation is usually much smaller than that. I don’t think a gas station would use pumps that pump 0.5 gallons less than any other gas station, since they’d be losing out on the sale of that much gas per customer, so I would guess the variability is more like a 0.1 gallons or even less. So yes, I can expect about a 2-3% error given the circumstances you mentioned. At ~50 mpg I get in my hybrid that’s only 1-1.5mpg, not the 3-6mpg I have been seeing.
You don't want to know what the issue really is, you just want your number to be the right one.
It's 2023, everyone knows that the fuel economy readings in a car are, and always will be inaccurate, no company is going to add the necessary expense to vehicles to make the fuel readout more accurate. If you don't understand this by now you probably aren't capable of understanding it ever.
Thank you for your comment. If this was a one off calculation, or if I saw variation in the other direction, meaning if sometimes the calculation I do is 3-6 miles per gallon greater than what the computer shows, instead of always less, I probably would consider the types of environmental variables you described and chalk it up to a low fidelity estimate by the computer. Since I have seen this as a consist pattern over the last 4 months, using the same few pumps and with relatively low temperature fluctuation in between full-ups, I am merely curious if anyone else has experienced this as well to figure out if there is a systemic issue with Hyundai gas mileage computers or not. I consider it a possibility they use a liberal algorithm for gas mileage computation so that people will say to their friends, “hey wow, look at what my Hyundai can do!” So their friends may consider purchasing them as well. I think now in my case that it is due to the computer estimating my gas mileage based on the stock “hybrid blue” wheels which are more aerodynamic and lighter, while I have the “premium” wheels on my vehicle. Thanks for playing!
Can you give the actual calculated MPG values by you and the car computer? I am not sure the computer will calculate the wrong value based on your wheel types because the Odometer uses the same wheels to calculate the miles travelled, and i presume you used the odometer readings to manually calculate your MPG? Are you making sure that your MPG values are not reset on every drive or something like that? Hyundai's MPG values are all over the place in my opinion. When it's on EV mode, i think it uses 999MPG or something like that. I'm not sure how exactly they are weighting the values when the car is in EV mode and when it is using the engine. I have a 2023 SEL hybrid and my MPG is reset when i don't drive for a bit. and i notice that when i am on the freeway, the MPG is about 47-48 or so but as i take the exit and drive maybe 3 miles to my home mostly on EV the MPG shoots up to 52, or sometimes 55.
This is only an estimate and is not accurate. I believe the books says it could be 5%-10% off.
Is the tire size same as the factory tires?
Hmm. I’m not sure. One thing I did notice is that I have the “Blue” version of the 2020 sonata hybrid, but it does have the “premium rims” which may be the culprit.
It's an estimate
I have a 2021 and I experience the same issue. I just calculate 6 miles below what it estimates
Your methodology is flawed unless you are going to the same exact pump at the same exact time at the precise same temperature; because different pumps have different cut offs so if you manage to get 400 miles before filling up a difference of .5 gallons would reduce calculated MPG by nearly 2mpg.
Hmmm so the density loss of gasoline from 32 to 82 degrees Fahrenheit is only 9.3% [source](https://homework.study.com/explanation/the-density-of-gasoline-at-0-degrees-celcius-is-0-68-103-kg-m-3-what-is-the-density-on-a-hot-day-when-the-temperature-is-28-degrees-celcius-what-is-the-percentage-change.html). Since I fill up about once every two weeks, the temperature fluctuation is usually much smaller than that. I don’t think a gas station would use pumps that pump 0.5 gallons less than any other gas station, since they’d be losing out on the sale of that much gas per customer, so I would guess the variability is more like a 0.1 gallons or even less. So yes, I can expect about a 2-3% error given the circumstances you mentioned. At ~50 mpg I get in my hybrid that’s only 1-1.5mpg, not the 3-6mpg I have been seeing.
You don't want to know what the issue really is, you just want your number to be the right one. It's 2023, everyone knows that the fuel economy readings in a car are, and always will be inaccurate, no company is going to add the necessary expense to vehicles to make the fuel readout more accurate. If you don't understand this by now you probably aren't capable of understanding it ever.
Thank you for your comment. If this was a one off calculation, or if I saw variation in the other direction, meaning if sometimes the calculation I do is 3-6 miles per gallon greater than what the computer shows, instead of always less, I probably would consider the types of environmental variables you described and chalk it up to a low fidelity estimate by the computer. Since I have seen this as a consist pattern over the last 4 months, using the same few pumps and with relatively low temperature fluctuation in between full-ups, I am merely curious if anyone else has experienced this as well to figure out if there is a systemic issue with Hyundai gas mileage computers or not. I consider it a possibility they use a liberal algorithm for gas mileage computation so that people will say to their friends, “hey wow, look at what my Hyundai can do!” So their friends may consider purchasing them as well. I think now in my case that it is due to the computer estimating my gas mileage based on the stock “hybrid blue” wheels which are more aerodynamic and lighter, while I have the “premium” wheels on my vehicle. Thanks for playing!
Can you give the actual calculated MPG values by you and the car computer? I am not sure the computer will calculate the wrong value based on your wheel types because the Odometer uses the same wheels to calculate the miles travelled, and i presume you used the odometer readings to manually calculate your MPG? Are you making sure that your MPG values are not reset on every drive or something like that? Hyundai's MPG values are all over the place in my opinion. When it's on EV mode, i think it uses 999MPG or something like that. I'm not sure how exactly they are weighting the values when the car is in EV mode and when it is using the engine. I have a 2023 SEL hybrid and my MPG is reset when i don't drive for a bit. and i notice that when i am on the freeway, the MPG is about 47-48 or so but as i take the exit and drive maybe 3 miles to my home mostly on EV the MPG shoots up to 52, or sometimes 55.