Our car is still new but I have noticed the few times I filled up when it says empty and the fuel light was on - but it only takes 16 +/- gallons - is this typical? Is my fuel gage normal?

Yes, the "miles to go reading" will read zero on our SL and the light will come on, it is a failsafe so that you do not rely solely on the "miles to go feature" or the digital gas reading.