In the area I live in (MD), gas comes in 87, 89, and 93 octane. I was talking with a friend of mine about the octane writeup and we got talking about what each of has to use for our vehicles (he only needs 87, I need at least 91 on mine). He said that he used to fill 89 octane but was frustrated by the huge price gap between it and 87. So he would fill up around 2/3s of his tank with 87, then do the last 1/3 with 93 since that would effectively make "89" octane, but cost considerably less. The thinking goes like this... 87 octane is equal to $n/gal, 89 octane is equal to $n+0.20/gal, and 93 octane gas is equal to $n+0.30/gal. So, instead of filling say 15 gal of 89 octane (=$n+3.00), he fills up 10 gal of 87 octane ($n) and 5 gal of 93 octane (=$n+1.50) which effectively saves him $1.50 each fillup. Sounds kind of funny doesn't it? I do admit that I've now noticed that many stations have a disproportionate price increase between 87 and 89 fuels, but not as bad with 89 and 93. In theory, this should be correct, but in practice, I'm not so sure. I suppose it is a cheaper way to get effectively 89 octane fuel, but I've never had to worry about it. However, with a truck like the Tundra, those that want slightly higher octane may be able to do that using this method because a truck will benefit most from this apparent "loophole" since the gas tank is large and the effort is more worth doing (i.e. at 24 gals, the savings will be $2.40 each time), though personally the difference isn't enough for me to make the effort if I needed to... what do you think?