My display says I do about 425 miles to the tank. I tested that theory on a drive up to Ottawa a few months ago, and it did indeed get to about 375 miles or so before it showed me the low fuel warning. However, on my day to day driving which involves 80% highway and 20% city, I average about 360 miles to the tank. I have noticed that where I get gas from has affected my MPG. When I stick to Sunoco, or 76 I get the above numbers. On the off day that I have no choice but one of those small "unknown" stations, it drops a bit.
To save gas I just stick to using the cruise control. I also noted when I drive in W mode, I get a bit lower MPG (especially in the city) than I do in S mode.