Theoretical, But Not Proven
according to the manual, the '95 infiniti J30 has a 19 gallon tank. when the indicator light comes on, the car takes just about 15 gallons, there for leaving 4 gallons in the tank. with my car getting ~20MPG with premium gas, that would give the car about 100 miles to go, once the light comes on.
Sounds about right. Most cars get a really good distance on their reserve tank. It's just that you shouldnt rely on it regularly.