ralper

I keep very detailed records for my S2000. Aside from every drop of gas that has gone into the car (including the brand, price per gallon, location and etc.) and all service, I can also tell you every time I cleaned the windshield or vacuumed the car, and just about everything else that I've ever done to the car. It's pretty simple to do using an excel spreadsheet with separate pages for various tasks.

I'm not quite so detailed with my BMW. I can tell you every drop of gas, oil and service, but I can't tell you about cleaning the windshield or vacuuming. But, this is my daily driver, not my prized possession.

All kidding aside, I have found that the records come in handy. For example, I knew when one gas station that I was going to needed to have it's pumps recalibrated just based on the mpg that my spreadsheet was calculating for this station and the others that I use. I also found out that even though buying gas at Costco is cheaper per gallon, it is more expensive per mile (based on my spreadsheet's calculations of a number of tankfulls at Costco compared to a number of tankfulls at other, name brand stations. The thing is, these can only be discovered if you keep records over time.

Aside from that, I keep the logs just for the fun of it.

valentine

I have noticed that certain brands of gas do not burn as efficiently as others. I bypass those stations even if I have to pay more to get better gas. I do not buy gas from Costco or Sams for that reason. I have noticed, however, that Kroger's gas does well in my car and in our Grand Cherokee.

Kyras

I've heard that Costco gas doesn't get good mileage but in my experiences, it's made no difference. I use Costco gas whenever I can and seek it out.

Scooterboy

I have found that all gasoline is the same until they add the different additives at the distribution terminal.

I use to work near a BP terminal. All day long there were only BP trucks coming and going but after midnight any and every brand truck would pickup there.