It will depend on how you drive, but you can likely get around 41 miles after the light comes on.
As per Autoguide.com, most of the time the fuel tank reserve is about 10-15 percent of the overall size of the tank. A 2012 Jeep Liberty gas tank holds 19.5 gallons so 10 percent of that is about 1.9 gallons. If you multiply that with the car’s 22 mpg rating in combined driving conditions, you’ll get additional 41.8 miles from your car after the warning comes on.
A careful note of caution, constantly running your car off its reserve fuel tank may cause damage to your vehicles fuel pump.
How you drive and take care of your vehicle can have a big effect on how much fuel you use. Check out these simple tips to save money and reduce pollution shared by Ucsusa.org.