I had a similar issue as the Dec 31, 2019 Bridgewater, NJ report. My CX-9 stopped operating on the Mass Pike (Route 90, major highway) in Boston. My gas gauge read half tank and range read 191 remaining. Upon a tow to a gas station, sure enough it took 19 gallons to fill-up, which means the tank was empty and I ran out of gas. This was an extremely dangerous situation as I had my family in the car (wife and 2 young boys), and we broke down in the fast lane (left lane) on a part of the highway that had no shoulders. I am grateful we're safe, but this is a major problem!

The Mazda dealer told me they suspect this being a software issue and they need to reset the software. As of this writing (on Feb 25), it was not done yet since I decided to get rid of this car as my first priority. I'll be following up with Mazda on the fix, and in turn, letters to Mazda USA and other consumer protection agencies to make sure this is properly addressed for other Mazda owners.