This thread pretty much has been covered...octane has a bunch of times as well. Run only the minimum required octane else you'll be wasting money.

At a stop light, when it turns green, turn off the A/C until you're at about 30-40 or so, then turn it back on. I have to do this anyways as my car is pathetic and slow even with the A/C off and I can feel a huge loss in power from the extra load.

As far as 93 oct. having less BTUs than 87, I didnt think that was true...I thought all levels of street octane had the same levels of BTUs