I have a 2001S, always put 91 octane in. 100% city use with 50% stop & go. Harsh conditions, and as a result I get around 16.5-17 mpg. I do wind it up when I get the chance though, 1st gear runs to the redline are a must if I find myself first at the stoplight.
I never clocked it even once, as it turns out gas was the cheapest thing I ever put in the car. I did use premium and enjoyed every single mile, if the car was getting 9 mpg, I'd have still driven it.