When I first got my Gigi, the dealer that had her didn't know beans about smarts and had been putting rreg unleaded in her. The first milage in town was about 33/34 mpg. After two tanks of 91 octane she was up to 36. The last tank which was 1/2 in town 1/2 Hwy was 41mpg.
I drive with the top down a lot. Also use the AC (top up) and keep up with traffic on the freeway (65-80MPH).
In a year and a half with over 15,000 miles I'm averaging 35 MPG. Best was 40 and the worst 31.
2008 Passion. 50,175 miles. Premium gas. Average mpg since May 29, 2008: 44.82. Last four fill-ups: 49.2 mpg; 48.93 mpg; 50.1 mpg; and, 49.89 mpg.
Just as a side note, I use a computer program called "gasbuddy.com" to keep track of my gas mileaqge. Great program & very user-friendly. Try it you'll like it
I have been using an app called aCar for my Android, love it. It keeps track of all expenses not just gas, e.g. services and other expenses. Also has a ton of reporting not just for your MPG.