On Sunday past we drove up to Orlando and back, about 190 miles each way. A few days before I filled the tank at Costco. My car uses premium gas, and gets very constant highway mileage of 30 - 31 mpg. It also calculates and displays current mpg.
On the trip up I noticed the mpg was low, so I reset the mileage calculator. It then showed 26 mpg over more than 100 miles of pure highway and a near constant speed of around 70 mph. Very strange. I did not refill until the tank was empty, and then tracked the mileage for the return leg. Back to the usual 30 - 31 MPG.
My conclusion is the gas I bought from Costco was really regular. I verified that my purchase was sold as premium. I plan to complain to them and the local regulatory agency, but before I do I wanted to ask if there would be another cause for this.
On the trip up I noticed the mpg was low, so I reset the mileage calculator. It then showed 26 mpg over more than 100 miles of pure highway and a near constant speed of around 70 mph. Very strange. I did not refill until the tank was empty, and then tracked the mileage for the return leg. Back to the usual 30 - 31 MPG.
My conclusion is the gas I bought from Costco was really regular. I verified that my purchase was sold as premium. I plan to complain to them and the local regulatory agency, but before I do I wanted to ask if there would be another cause for this.
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