Mileage difference, unleaded regular vs premium?

[Sailor602]

Recently I had a $1 per gallon discount for gas at my local grocery store; I was also about to make a 300 mile highway trip at 65 MPH. With that discount I decided to splurge and get premium gas, no ethanol. My fuel economy averaged 34.2 MPG for the trip, versus my typical 29 to 31 in shorter highway driving.

Has anyone else seen a significant mileage improvement with premium or should I attribute this to the almost pure highway driving?

[Rick Murphy (RicksVue)]

Ethanol-free fuel will give you a good (10%) MPG boost. That's probably at least some of the gain. I've found that mid-grade fuel suits my Green Line better than regular; it runs fine on reg, but is probably doing timing games to avoid knock that the mid-grade fuel can avoid. I can push over 30 MPG highway using regular, so it's interesting to see how much better premium can do.

[Trudy]

We've only using regular gas in our Hybrid and we do mostly city driving. My husband said it isn't getting what it's supposed to though. But in a recent trip to Florida (from Ohio) we spent only $70 in gas each way. I went over and over our gas receipts from the whole trip to see if I made a mistake somewhere, but I didn't. We'll have to do a regular mileage check to see what we come up with. So far we are loving the savings because we don't put gas in it very often. I'll have to tell him about t he mid-grade or premium.

[Sailor602]

Interesting comments. In the city (with a lot of stop and go) I only get 24-26 MPG with regular gas (less if my teenage son drives ). I don't know if mid-grade or premium would help much there.

But most of my driving is highway which is better mileage and easier for me to test. I also find that my average speed makes a difference. Doing 64 MPH instead of 69 MPH gets me another 1 to 1.5 MPG, and when I drive in Michigan and need to keep up with other cars (74 MPH or more) I drop to 26 MPG.

Thanks for the comments. I'm going to test this again soon and report back.