[Overdrive]

No way, something's off there. The Boxster has about a 16-17 gallon tank, so if you were bone dry you'd be filling up with close to that much...strange that the car is dying with seemingly 1/4 tank still in it.

I know my gauge can be a little funky at times, and when I first got the car it would not read full even when the tank was full...it would settle at around the 7/8 mark. When I picked up the car there was little fuel in it, and I think the float got used to being at that low position for a long time, maybe some corrosion even built up on the parts that were not sitting in fuel. Eventually this stopped and now it shows around that mark on a fillup and slowly moves to full as I drive away, then starts working its way back down. I guess the float is showing its age, but it still works, and I can drive right down to my low fuel warning light and still be running, not that I make a habit of it.

Your situation sounds really strange, though. I can't really imagine why the car would stop running with fuel left in the tank, or if it really is empty, why it would not take in enough fuel to its full capacity...something, be it mechanical or electronic, has to be tricking the car into thinking it does or does not have fuel when the opposite is the case.

Sorry I can't do more than speculate here, but I've never heard of something like this before.