What octane and brand?

[Unclviny]

Chevron, Shell or Texaco (the cheap stuff) for me, my OB (3.6) gets almost 28 on the highway.

Vince

[coolerbythelake]

The issue for MPG improvent is ethanol or no ethanol in your gas, not octane. Ethanol has lower BTU energy that gasoline so it will negatively affect gas mileage (in additon to being corrosive to engines not designed to handle it). But at least we divert our food supply to produce a crummy government mandated and subsidized, environmentally harmful fuel additive (note sarcasm). In the rare case I can find no-ethanol premium fuel I will use it. In Wisconsin about the only way to avoid ethanol is to go to dedicated premium fuel pumps that are outside of southeast Wisconsin. When I use ethanol free premium gas I document a 2-3 MPG improvement. Not a huge improvement but noticable.

[benamin]

I don't know your stations in the US but all I can add is stick with regular, here it is 87 octane. Stepping up won't net you anything but more fuel cost. I don't think we can get any fuel here anymore without ethanol, for a few years now, at least I haven't found any.

[Subyblue]

I've almost always used Costco gas in my '11 3.6 since getting it (and even before that with my T4R), and have never had a problem. If you get to the station early in the morning or late at night there is usually no line. Even with a line, I've not waited more than a few minutes, even in Medford Oregon, the busiest station I've been to. This morning in Citrus Heights, I was one of only three at the pumps at the time I arrived.

I use Costco because of the rebate I get for using AMEX (paid in full each month). I tried Chevron for a couple of tanks because others on this forum indicated better mileage. At the price/mileage difference there was no benefit in overall cost, and I didn't notice any improvement in performance. Besides, Chevron put a $100.00 hold on my card each time I used it (meaningless, since i don't come close to the balance, but it was the principle) Ok, you say, use cash--I could, but I chose not to.

JMHO

[coolerbythelake]

I switched to synthetic oil this past summer. I compared my last 10 tank fulls of gas to the 10 tank fulls over the same period last year (to eliminate any seasonal variance) and I documeted a 1 MPG or 3% improvement overall. Not huge but when you factor in the better cold weather starts and longer oil life I find it a net positive. Note: I change my own oil so the cost difference for syntheitc oil is a couple bucks a quart versus regular oil.

[147_Grain]

I get the lowest MPG at Kroger and the best mileage at Chevron.

[fun2drive]

I use regular. I have many times sat at a restaurant that looks over a Citco sub station watching the barges pump gas off into storage tanks. In the panhandle where I live we get all our gas by barge. Every brand of fuel tanker is there get refueled. I can only guess that the detergent additives and other additives for each formulated fuel is mixed into the fuel pipes filling the tankers. All fuel goes into 2 tanks so clearly the manufacturers must have "their" formulation which goes into the various company tankers. I always assumed each company had their own sub station but here that isn't true.
That said I have noticed no difference in mpg using various fuels in my area. However now that the OB is up north for a few months and it is 30F out from 70F I have noticed a 3 mpg loss. Maybe it is the fuel formulation or the temps or most likely both that caused this.
I don't know what higher octane would do to my mileage. I suspect nothing since higher octane isn't needed to reduce knock...

[Pool Runner]

I'm not really a bargain shopper when it comes to gas, I buy from whatever is closest to me at time I need to get gas. As an example I always try to fill the car up for my wife so she doesn't have to. So she will come home for work and say Ohh I need gas for the car, so I end up going to fetch gas just before I call it a night so to speak, basically I'm always going to the closest station to the house. There are at least 20 stations near me and they are all within 10 cents of each other +/- so I don't lose sleep over that.

With that said, my car struggles to pull of more than 27 mpg, and will if the highway is flat as a board and cruise is set 68-70. But it will easily get at least get 27 mpg. In the cars defense, we do have two fork mount type Yakima bike racks on the roof, so not sure if that is causing the drag.

[KaizerWilhelm]

76 Ethanol Free for me. It's only half a mile further than the Shell near my house so it's worth it. I have seen a slight bump in fuel economy since switching to the ethanol free petrol. If I can't find that, I go with Shell.

[upflying]

I buy 87 at Costco, runs just fine.
Costco always has fresh gas too, trucks make a dump at least twice a day at my busy station.