So, i’m sure it’s happened to everyone, but i am noticing HUGE differences in the quality of gas i get at different places. What’s worse, it really depends which day, rather than which place.

Example:
- I recently filled up at a Kroger gas station, on gas 4c/gallon cheaper than other places ($2.28 in GA - yes, i put regular in my E90 328i) and got a whopping 36mpg for the rest of my trip! Mostly highway, but still a few mpg above what i normally get on that route (~33).
- a week later i filled up at the same place and got 32, similar conditions, and the car felt rough.

Does this just happen to me????

I’m sure it’s not just you. I hate to say it, but I think only the big name fuel stations are good.

I use water/methanol injection, so I’m effectively driving on race fuel all the time.  no complaints from me.

I find that even at Shell/Exxon I get varying qualities… It could be that i am used to European fuel standards, which have a higher octane level.

Boosted, what’s that mix and how do you make it? Does it damage engines?

Mileage has so many variants. However, I too have found that I get better mileage from the small family owned G-ride down the street from where I live (Citgo, compared to Tri-par and Mobil). But to make an honest comparison it would have to be done meticulously checking the air temp, humidity, wind direction and speed, tire air pressure, car temp and probably more that someone with more knowledge could tell you, maybe even how clean the car is..chucks of mud could create drag, not much, but it all adds up. I think a well-maintained gas station is also important. If they have tanks that allow moisture to get in that could surely effect mileage. I’m not sure if this happens, but say your car is kept in a warm garage and you put cold gas in, could that create moisture in the tank?

Clarksonius once referred to petrol in the U.S. as “limp wristed fairy liquid”. 

Whatever…

But I too have noticed that my Gracie (yes, I named my car) reacts differently to different fuels.  Since she is a stately lady (150,000 plus this weekend!) I try not to upset her delicate digestive track….:^)

I talked to a guy who delivers gas to shell. He said there v power is a bunch of crap because they never tell him which octane he is carrying. He said when he pumps it into the station he just fills whichever tank is lowest. I am now using vp race fuel c16 in my car. It makes a ton more power because you can throw in more timing. I went from 374whp to 406whp just from switching and a quick tune on my ecu. I probably could have got it up to 420ish at wheels but I ran out of clutch hahaha.