Like cordrayj1 askd, how much is a "tank" for you. Sometimes the fuel gauge can be a little off so if it says you're empty when you still have a few gallons left. If your fuel light is on and then you top it off and only put in 10 gallons then you're getting average mpgs, but that means your gauge isn't reading correctly. But if you're putting in 14 or 15 gallons and only got 160 miles out of it, you have something wrong.

If it is in fact getting that bad of mpgs, you may want to replace your front 02 sensor if it's the original. Even if you're not throwing an engine light, a poorly functioning 02 can cause pretty bad mpgs.