2025 Mazda CX70, 6000 miles.

I was on a trip recently towing a small camper. I get 18-18.5 mpg towing. Full tank range is displayed as ~300 miles. I typically fill up between 1/2 and 1/4 tank, but decided to see when “low fuel” light would come on. 1/8 tank left and a reported remaining range of 40 miles. No problem as there was a major exit in 20 miles. But, within the next 5 miles, the gage went to E and zero miles range. This was at 270 miles vs the 300 reported 1/8 tank and a few miles before. I was 3 miles from a gas station and puckered the whole way there, but made it. Filled up and it took 15 gallons.

The tank is supposed to hold 19.5 gallons, so I should have had 4.5 gallons and almost 80 miles left when the gage was on E and range was zero miles. I get that they want some reserve fuel capacity, but 1/4 tank? And, why such an abrupt reduction in the gage and reported range in the last 1/8 tank?

im wanting to run the tank empty to prove the 19.5 gal tank capacity, but am not brave enough to do that. 😊

Love this vehicle, but this is odd.

Do I have a gage problem or have others had a similar experience?

 

Gotta post the year when asking service related issues.
miles would help as well

 

Updated the post. Thanks.

 

Nothing you really posted is the best way to determine your actual tank capacity. Nor do I see a problem in the reporting. The only possible cause would be if the sender was damaged or debris introduced in the tank during fueling.

The other often misunderstood is how the gauge reads for the driver and not what is actually physically represents because of the tank internal size and shape as well the parts inside the tank. In other words, 1/4 tank does not always empirically represent 1/4 volume remaining.
The other consideration is if you are trying to completely determine gas volume to mile you need to frit do several calculations and set a standard or base line for testing of how you determine the fuel consumption vs volume.
This mean you need to fill the tank at or close to 1/2 indicated on the fuel gauge at a gas station that you can return and use the EXACT fuel pump and also the same time period of the day of the same measured ambient temperature. So better to do this very early in the morning before ambientes start to climb. Then you should drive a normal route that you would do over several days. O This will for the most part create input that effects a better reliable calculated result.

Once you do that you will have a baseline of approximate fuel consumption you will be able to better determine your DIY method of tank gas volume to the gauge indicators of fuel reaming when you get an indicated 1/4 or lower fuel tank level.

Or you can go to the dealer and state what you think might be a concern and they will enter it on your service VIN and do a diagnosis of your fuel monitoring system. But in this case there is only very basic tests unless you leave your Mazda several days and they assign it to a service tech that will drive it back and forth to and from work until what you told them can be duplicated and then checked? But as I suggested I can see nothing that indicates a problem?

IMHO if you are traveling I would never get to 1/4 of a tank and not have a planned refueling stop planed in advance . To me on trip is 1/4 means get gas NOW!