I ran my car down to empty on the fuel gauge and one mile left on range indicator. I then filled up with 16 gallons ($3.88/gallon!). It would not take another drop.

I then looked up the tank capacity and found that it should hold 18.8 gallons (2006 Lexus GS300). On my last tank, I averaged over 29 mpg, so Lexus has built in a pad of more than 80 miles! I do believe that you shouldn’t be burning the last gallon of gas from a car as the water and junk settles to the bottom of the tank, but that seems like an excessive pad. The important thing is to know about the pads and not sweat it if you seem to be in trouble. Somehow the budgeting process from my Time Warner Cable days came to mind…