Last time the car said the remaining range was 5 miles, I filled it up and I think there were a bit more than half a gallon left in the tank. So in reality, it could go another like 15-20 miles (highway). Not bad...
EDIT: Just found out the tank is actually 14.5 gallons. There was another gallon or so left. So 25-30 miles?
Depending on how you drive. Then again I know how anyone who would floor it with the gas light on.