I have a 2003 MP5. I get betwn 27 to 29 mpg in town. I just went on a trip to Augusta, Ga. I still got 27 to 29 mpg. the speed was 73mph at 3200 rpm. I expected to do about 32mpg Is this normal or do I need to check something out.. I have replaced the sparkpluge with NGK and the air filter. both were replaced sometime in the past two months. I hope someone can help me.