On vehicles that read 0 miles to empty you usually have at least 1 gallon to 1/2 gallon left.
The distance you can go on 0 miles to empty depends on how much gasoline your vehicle uses but for most cars and vehicles you can sometimes go as far as 10 miles to 30 miles.
With a truck you may only get 5 to 10 miles on 0 miles to empty and on a car you may be able to go 30 miles on 0 miles to empty.
Even then it's best to add gasoline before you get to 0 miles to empty as it's harder on your fuel pump to run the tank dry.
The next logical question after your gas light has turned on is how many miles until empty do you have before your engine shuts down?
There's no hard and fast measurement — each automaker turns the light on with different amounts of gas left in the tank — but a general rule of thumb is between 30 and 50 miles.