I never knew about this but thank you all for the info!

 

I fill it until it shuts off automatically. The most I have ever put in the gas tank was 17.124 gal. There was 0 miles left on the fuel range indicator. The Jaguar manual indicates that the gas tank is 18.80 gallon. I doubt I am over 1½ Gallons from full. I think the fuel range indicator is very conservative.

 

Yes, there's a reserve - best not to dip too far into it, as I believe actually running the tank dry is a Bad Thing (airlocks in the fuel system).

Anyway, human nature being what it is, if you know there's an 'x' mile reserve, you tend to start building that into your "Can I make it?" calculations. Which then increases your risk of being stranded.