The fuel gauge isn't progressive at all, and shows full long enough to make me think its stuck.
The later cars have a low fuel light, but I don't really trust that. I was once caught out in the middle of nowhere when the light popped on. Its big and orange, and I travelled the next 35 miles on a feather throttle, but filled up safely. I don't recall the numbers, but there was still maybe a gallon in the tank.