A 15 Gallon Tank, An 11 Gallon E
I bought a PT Cruiser in 2000 (MY 2001), and over the 6.5 years I've owned it, I've become accustomed to its quirks. The gas gauge is one of those.
I have a 15 gallon tank, and the most I've put in it is actually 15.4 gallons, so I know the manual isn't lying about the tank's capacity. The Cruiser has two gas lights, if you will: a single ding at the beginning of the red part of "E", and a triple ding and flashing when it gets through the red and truly onto "E". If I fill up in the first case, the tank usually takes 11 gallons; the second, usually 12 will go in.
I get around 23 MPG in my Cruiser, so the triple ding gives me about 70 miles, and the regular closer to 95! (I registered 80 as the middle ground of that.)
At least I know it would take a lot of ignoring to truly run out of gas.