Hello, I am trading in my car for a 09 Impala SS (122k miles, garage kept, completely stock). I was wondering what is the real world MPG to expect from this car? My car was suppose to get around 28 mpg highway but i averaged maybe closer to 21. Looking for results from both with and without the active fuel management enabled. I know people that normally buy these cars don't care for fuel economy but I am just curious on what I should expect.