What's left people guessing, however, is exactly how far you can go when the gas light comes on, and since there's no established standard for reserve fuel capacity, it varies with each automaker and model. But thanks to the website Tank on Empty, which has a searchable, user-submitted database, you can have a better idea of your on-empty range.

According to the site, there are some surprising low-fuel winners: the mammoth Ford Excursion may guzzle gas like a cargo ship, but it also boasts one of the longest ranges, averaging 85.12 miles. That beats the eco-conscious Prius, which can run for 55.12 miles, or a Porsche 911 Carrera, which could quickly leave you stranded on the shoulder with its average of 23.82 miles.

But don't get emboldened by the data to run your car on fumes, because continuously doing so can wear out the fuel pump. Most modern vehicles use an electric fuel pump, which is inside the fuel tank and relies on the gasoline to keep it cool; hence you'll want to keep the tank at least a quarter full to prevent premature wear.