It has been an average of 25-30¢ between grades here for the past couple of years or so. Means 50-60¢/gallon between 87 and 93 octane. I run premium in the Honda since it returns an easy 5-6mpg better fuel economy (~100 miles per tank), despite the car being designed for "regular" 87 octane fuel. The cost is a wash between the two, but the car runs better and I can go longer between fillups with the high-test.

The SL gets 93 octane on principle. It will run on 87, but once it gets hot, it starts pinging which doesn't do it any good.