Hyundai Repair: 2004 Sonata door locks, fuel economy, 2004 hyundai sonata, hyundai sonata

Question
I recently purchased a used 2004 Hyundai Sonata sedan V6 and have noticed 2 problems.  First, the driver's side power door lock locks all doors but does not unlock all doors like the passenger side does. Second, I have some horrible gas mileage, we're talking 1/4 tank to 30 miles. Nowhere near the 19 miles per gallon listed for city driving. Help.

Answer
The door lock is easy one, the master switch is bad on the drivers door,need to replace it or if you have any know how about switchs you can take it apart an cl;ean it an put it back togther,

Now the gas milage need to know milage an if there are any codes,in the computer.