A couple of things about our cars and commutes.

We have only one gas card - for Mobil. We both have Speedpasses - the best little piece of consumer payment technology out there. So, needless to say, when we get gas, it's been exclusively Mobil.

there are quite a few Mobil stations in our area, and in what may be some collusion-thing, they all change their pump prices at the same time, always to the same price. When somebody doesn't, we always joke and say "they must not have received the fax".

So every station near our house has the same gas price. Further away, you run into different municipalities that could (though I have never checked this out) tax rates, so the prices may be 1-2 cents off.

Now, another thing to share is that I have only used one grade of gas in the lifespan of my 1997 Infiniti I30 - premium. I started it out that way, it's always run GREAT, so I'm not changing it, even when the damn oil prices were skyrocketing.

Now that I'm working in a different building, my commute takes me a different route, past a different Mobil station.

It took me a few weeks to verify that this was indeed happening - the price changes at this station were different.

It turns out that - for the last 4 weeks, at least - this station would drop their premium pump prices by 4 - 6 cents, while keeping the other grades the same price - each Monday. The next day, the prices would all be back in order.

Needless to say, I've been stopping each Monday on the way home to fill-up, whether I needed to or not, to take advantage of this odd pricing scheme. I really would like to know what the "why?" is behind this. I really don't care, since this fits my needs very well! I'm just curious...