You can find out exactly how far it will go if you do a little bit of math. Don't be so lazy.
Fill the fuel tank full. Make a note of the miles on the odometer.
On your next fill-up, fill the fuel tank full again and note the miles on the odometer again. Also write down the amount of fuel it took to fill the tank full.
Subtract the first odometer reading from the second odometer reading. This will tell you how many miles you went between fill-ups. Divide this number by the amount of fuel you used to fill the tank full. This tells you how many miles per gallon you got on this tank of fuel. If you repeat this process a few times and average the results your MPG reading will be even more accurate.
Now look in your owner's manual. In the capacities section it will give the size of the fuel tank. Multiply the miles per gallon from the earlier calculation by the size of the fuel tank. This will tell you how many miles you can go before you run out of fuel.
This is much more accurate than a wild guess.
Remember to allow a little extra fuel for reserve. Your goal is not to run the rank completely dry and leave yourself stranded on the side of the road.
