Too many variables to consider; there is no way for us to tell you what the issue is.

 

whats your temperatures been on your last fill up.. as well as tire pressure..

 

Still average 26 miles to the gallon, temperature's been in 40's. Embarrassed to say never check my tire pressure, rely on my low tire pressure monitor to come on to tell me, but it never does.

 

Sounds like your asking us to assume the same city/highway driving pattern between fill-ups and this is happening since your last fill-up? Still getting your gas at the same station? You haven't switched grades or from non-ethanol to 10% ethanol mix fuel? Things like restricted air filters & dirty oil happen over time so I'll exclude that. Temperature change effecting tire pressure has bearing (lower temp=lower pressure=lower gas mileage). Had any service recently? Possible MAF sensor issue. They usually fail suddenly. How does the car idle? Does it run almost as well cold as it does after it's warmed up? I have a 2014 so this has my interest!

 

Are you aware the TPMS won't trigger until a tire has lost 6-7 PSI? You're just asking for trouble!

 

when i got my new 2018 cx-5 it was 82F 2 month later there was over a 50F temperature drop, i decided to check my air pressure... i was shocked to see i was 7 psi low in all tires..

 

I take it you don't follow American football; ever heard of the DeflateGate scandle?

 

Thanks to all who replied. I will get into habit of checking air pressure more often. Will take in for 45,000 mile service next week and ask them to check this problem. Did not know TPMS won't trigger unless 6-7 psi lost. Only time in past came on when I ran over a nail and had a flat.

Car idles fine cold and warm

Yes, remember defltate gate, I was just suddenly surprised why such a 100 mile distance reading.

Thanks again, enjoy my CX5.

 

Its been warming up lately for me too, fuel range has been dropping on fill up. Cars will burn more fuel when ambient temperature is high.

Cold air is more dense, & will require less petrol to combust than warm air.

Also with warmer weather, you will most likely be using A/C more, which will use more fuel too.