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Low gas mileage in Calif

All of a sudden, last fill, I noticed both cars had done lower than usual mileage.

While both have almost reached half tank, the mileage is low around 60 and 70. These are integras. Typically do 22-24 mpg in town. There is no sign of breakin. Not sure if they can open it without getting into the car.

Any of you in northern Calif facing similar issues due to wheather …?

How are you figuring the gas mileage?
You should be dividing the gallons used into the miles driven. I don’t see that in your post.

A full tank does more than 200 miles.
It is about half tank and only did 60-70 miles - had it done over 90, I would not have posted here. To add to this, last time, when I filled it up, it gave around 18 - giving me some anxiety.

Your gas gauge is not reliable for calculating fuel consumption. Rather, fill your tank precisely the same way several times (same station, same pump, stop at first click each time) and do the math. Then you’ll know if you should be concerned.

The case you mentioned may be that you filled differently, that is, not truly full the prior time, then overfull the second. That’s why you need multiple fills for accuracy.

It’s possible you have a problem, but you can’t judge that with an estimate using your gas gauge reading. Do you have a check engine light showing on your dash?

No engine lights. I filled up one car with about 4 gal. Improved to 20MPG - but it is unreliable as it is with about 4 gal.

You cannot use your gas gage to estimate miles traveled. It isn’t designed for that purpose. The tank isn’t a standard geometrical shape (like a cylinder or a cube), so a drop of 2" in level near the top of the tank may be a very different volume than a 2" drop in another part of the tank, and “empty” leaves a gallon or two in the bottom. The gage on a 14 gallon tank typically reads “empty” when it gets down to about 1 to 2 gallons.

You need to use your odometer to measure miles traveled and the volume readout on the pump to measure fuel used. And because the pump handles themselves don;t all shut off at the same fill level, it takes a few fillups averaged out to get any accuracy of mileage. And even that will vary depending on weather, # of passengers, and type of driving.

Don’t forget to factor in the lower mileage you will get from the winter blend of gasoline in California. The state even instituted the start of winter gas season earlier this season to increase fuel supplies.