Hi all! I've had my 2010 Mazda 3 with the 2.0 for about a year and I've noticed I get about 19 to 21 miles per gallon City. Has about 115,000 mi on it. I recently bought NGK ruthenium spark plugs and denso ignition coils, which should get here on January 3rd. I drive like an old man 95% of the...