How many miles you get on a specific tank of gas depends on how you rode that tank of gas...
1/4 tank indicator comes on when it thinks you have 1/4 tank. If you get the 40-42 mpg per the manual you have about that left before running dry.
Low fuel light and count up start about 1/2 way through the 1/4 tank left and in general it is best to get gas before that count-up hits 20 to be on the safe side.
All that said I have sweat it out a few times and the most I ever added was 3.8 gallons and I was at 27 on the low fuel count-up. Have not run it dry so don't know exactly how much fuel it takes and really don't want to find out
Then again .2 gallons at 42 MPG is just over 8 miles so I was close enough to running out of gas for me!!
After Ivan's flash I get 43+ mpg so in general a tank for me is 150 miles easy.
P.S. A GPS or smartphone is really helpful when looking for gas if you are low and in unfamiliar territory...