MPG and changes for improvement
 

I'm new to the forum. I just purchased a 2007 altima hybrid with 65,000miles.
My first tank of gas I averaged 33.45 mpg. The car computer was saying 36.9mpg. Since then I did an oil change with 0-20 oil, installed some Michelin saver AS tires and filled the tank with ethanol free gas. Currently the car computer is saying 40.9mpg still have a little over a half of a tank to go. Has anyone else put anything on their car to help improve fuel economy?