When I worked in HVAC, and drove my work van 300 - 500 miles a week, I used to get 10 MPG on Shell gas. I started filling at Cheveron or Mobil gas stations and got 11 MPG, so stopped buying Shell gas. Arco, Shell, and BP are all the same brand of gas, I would get 10 MPG with those brands. 11 with Cheveron or Mobil.
With my motorhome, I normally got 7 MPG at 63- 68 MPH. My last trip, I could not afford the gas, and so set the cruise control at 55 and bought 92 octane gas. One section, I got 8.8 MPG, while going from San Diego to Bakersfield, going over some steep mountains in the process.
Congress will tell you that you get no better fuel mileage while using higher octane fuel. Test it for YOURSELF in your vehicle. You should find a difference. The fuel management system will find the engine is not pinging, and will advance the timing, you will get more HP out of the engine, and it can run leaner without pinging.
All modern engines have fuel injection, and a ping sensor. When the electronics detect pinging (ultrasonic pings, nothing you could hear) it can do three things to reduce the pinging. Enrichen the fuel mixture, changing the timing to make less power, downshift to a lower gear, so the engine spins faster. All three will decrease the MPG.
Those with a Ecoboost will find that the fuel mileage is significantly reduced while towing - unless they use higher octane fuel. Running solo will also provide better mileage with 92 octane.
Fred.
Money can't buy happiness but somehow it's more comfortable to cry in a
Porsche or Country Coach!
If there's a WILL, I want to be in it!
I havn't been everywhere, but it's on my list.
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