HPFP and gas gague
 

So, I've been thinking about why our cars claim to have roughly a twelve gallon gas tank, but when the fuel light comes on it only takes around nine gallons to fill it up.
I used to own a jetta turbo diesel, and the newer ones that came out after the EPA regulations mandated that all new diesels must be equipped with a diesel particulate filter or some other means of filtering out the soot from the exhaust, they were equipped with common rail fuel injection, and a high pressure fuel pump(HPFP).
There were a large number of these newer diesel cars having issues with their HPFP's failing, and one thing many of them had in common were that they ran out of diesel at least once. So I just wanted to give a warning to not try to see how many miles you can squeeze out of a tank because of the risk.

Typically the fuel cools the pump, so running them dry can cause damage. The same applies to in-tank low pressure electric pumps.

IIRC we have a 13 gallon (or was it 13.2?) tank. I was forced to run the tank dangerously low once, and that was a 12.4 gallon fill up. I typically fill up when the light comes on, and even that takes just shy of 11 gallons to fill.