Cadillac Repair: 1991 fleetwood fwd bad gas milage, fuel mileage, inflation pressure

Question
I have had all spark plugs changed wires dis.cap air filter used to get a reading of280miles on atank of gas now 196 miles same amount of gas to fill the tank actually getting 146-160 miles out of a tank

Answer
If your going by the fuel mileage display mounted on the dash, This is only an AVERAGE amount of fuel being used. It calculates fuel mileage used even when the car is just sitting still idleing in it's computations. It is NOT that accurate.

The one thing that most everyone over looks is the air pressure in your tires. make sure thaey are at the maximum recommended inflation pressure as stated on the tires.