Lately, I've been seeing increased gas consumption in my Mazda and it's really depending on where I get the gas; whether it's from Shell, Exxon or Chevron. I know this subject is nothing new but just to share my experience, I've notice that while keeping my driving habits the same across the board, Exxon seems to give me better gas mileage followed by Shell and then Chevron. I know a mechanic who never gets gas from ARCO even though this place usually has the cheapest gas around.