We recently completed a 3300 mile, sixteen day trip through seven states in the west and southwest US in our E-500. We got over 23 MPG at an average speed of 53 MPH for the entire trip and noted gas mileage was about 2 MPG higher with gas purchased in states outside CA, such as NM, AZ anc CO.


Another observation was that the highest speed sections consistently gave the highest mileage as noted in this image of over 27 MPG for a 142 mile segment at an average speed of 76 MPH.


We saw beautiful fall scenes and had no car problems at all.

Do you happpen to recall your start and stop points for the 142 miles @ 27.3 MPG?

I wonder if the gas your bought outside California didn't contain ethanol ... that might explain the mileage difference. So far as I can tell, the purpose of the federal mandate requiring ethanol in California gas is to transfer wealth from California drivers to Midwestern agribusiness corporations like ADM. Or did you get some 93-octane gas outside California?

The 142 miles was from Flagstaff on I-10 heading west towards Kingman, AZ. We got gas and I noticed the high mileage so took the photo above.

This is not the first time I've noticed higher mileage outside of CA, and I believe you are probably right about the gas not having methanol at many stations but I didn't really pay attention to that when refueling. We got 91 octane everywhere and no super grades. On an earlier ~300 mile run (not on this trip) from Grand Junction to Fort Collins, I got 27.4 MPG and averaged over 74 MPH.