A tank of gas probably wouldn't get you out of the fuel station without a tow truck.
Well the tank is 21 gallons BUT it is really a 19gallon tank with a 2gallon reserve.
If the little light is working correctly there is a yellowish triangle that comes on by the R when it kicks into the reserve portion.
MY range is normally quite low on a tank because I normally refill around 1/2. If I used the majority of the 19 I'd probably get mid 500s, but this varies all on the type of driving so....