According to the manual, the gas light should come on when approximately 2.2 gallons are left in the tank, so the number of miles left depends on conditions. If you're doing about 55 miles per hour, I think at least 60 miles would be do-able, maybe 70, but I wouldn't want to test the theory myself enough to find out for sure.
I have pushed it probably 50 miles though. I was lucky enough to have the roads to myself, so I was doing 50 mph in a 55mph zone, which seems to be the most efficient speed, at least in my automatic transmission. I use ultragauge to judge instantaneous fuel economy, by the way.