They never made a turbocharged Impala. Could you be referring to a supercharger?
You need to be a little more accurate on the MPG you are getting. How far you go on a tankful doesn't tell us anything accurately. We need to know how many miles on how many gallons to calculate MPG. Fill it up, record the mileage. Drive it until 1/4 tank and fill it again. Record the gallons it takes and the mileage driven since last fill up.
Saturday, November 1st, 2014 AT 5:50 AM