I filled up once exactly at 0 miles to empty (MTE), the gauge was right on the E mark - took 14.4 gallons. I went 24 miles past E and put 14.8 gallons in on another tank.

My estimation is you have ~ 2 gallons in reserve when the needle rests on the E. The gauge reads noticably below E when you go further. I've gone 63 miles past E before and not run out.