Gas Mileage Estimates Way Off and Gas Light Comes On Too Early?

I have a 2025 Hyundai Santa Fe Hybrid Calligraphy AWD, and I’ve noticed some odd things about the gas mileage estimates and the fuel gauge.

First, when I fill up, the car estimates ~558 miles on a full tank. But the most I’ve ever gotten is around 430 miles. Should the estimate really be that far off?

Second, the gas light comes on when the car says I have about 58 miles left, which feels a bit early. I drove it down to 21 miles left, and when I filled up, it took 15.55 gallons in a tank rated at 17.7 gallons. That means there were still over 2 gallons left. Is this normal? My previous car had less of a reserve.

Overall, the Santa Fe gets better mileage than my old 2011 Hyundai Sonata 2.0T, but I feel like I’m filling up more often. Could this just be because of the slightly smaller gas tank? It’s frustrating, but maybe I’m just not used to it yet. Any insight would be appreciated!

Hyundai seems to keep 1.5-2 gallons in reserve. It’s a common thing to prevent you from running out of gas, but I agree it’s annoying. European cars I’ve owned before were more accurate.

Lex said:
Hyundai seems to keep 1.5-2 gallons in reserve. It’s a common thing to prevent you from running out of gas, but I agree it’s annoying. European cars I’ve owned before were more accurate.

My old Sonata had about a 1-1.5 gallon reserve, which felt fine. Over 2 gallons seems excessive.

My Mazda has a 3-gallon reserve in an 11-gallon tank! They claim it’s to keep the fuel pump submerged and running cooler.

Morgan said:
My Mazda has a 3-gallon reserve in an 11-gallon tank! They claim it’s to keep the fuel pump submerged and running cooler.

That’s wild! I’d have a hard time accepting that much of a reserve.

I’ve mostly had Toyotas, and they usually have 1-2 gallons left when the gauge says empty. I wouldn’t be surprised if Hyundai does something similar.

The car is just optimistic. The 530-mile estimate matches the advertised fuel economy, but that’s under ideal conditions. Realistically, you’ll get less, especially if you drive casually. I’ve seen the same with my car.

@Van
I get that it’s optimistic, but being 25% off feels like more than just optimism.

Hux said:
@Van
I get that it’s optimistic, but being 25% off feels like more than just optimism.

It adjusts based on how you drive. Mine started showing more realistic estimates after a few fill-ups. It’s probably still learning your habits.

@Van
It’s been my daily driver for a month now, so maybe it just needs more time. I’ll keep an eye on it.

Hux said:
@Van
It’s been my daily driver for a month now, so maybe it just needs more time. I’ll keep an eye on it.

Same here—got mine about 4 weeks ago. Let’s see if it gets better. Either way, it’s great mileage for a car this size!

@Van
True, the MPG is solid. I just didn’t expect to fill up this often.

@Van
It does adjust. I’ve noticed similar behavior in my Mazda, especially on hilly drives. The estimates fluctuate based on conditions.

Every car I’ve owned has had about 2 gallons left when the gauge says empty. The Santa Fe seems pretty normal to me, but the mileage estimates are definitely optimistic. Even the MPG display on the dash is usually 10% higher than the actual MPG when calculated at fill-up.

@Landry
My last car was 15 years old and had a smaller reserve, so this just feels weird to me.

Both the miles left and MPG estimates are based on recent driving patterns. If you were hypermiling, the system probably thought you’d continue driving that way.

Car manufacturers add reserves to protect the fuel pump, prevent engine issues, and account for sloshing in the tank. It’s not ideal, but it’s better than running out of gas. If you want to avoid this, try keeping your tank above half full.

@Fin
I get the logic, but I’ve only ever gotten 430 miles on a tank, so I’m not sure where the car is pulling 558 from. I guess it’s still learning, but I have a pretty consistent commute, so it has data to work with. As for keeping the tank above half full, that’s great in theory, but it’s not always practical in real life.