Just purchased a 2011 RX-350 AWD with 19,500 miles on odometer. Now at 20, 500 with several long trips planned next month. Currently getting average of 20 MPG in mixed driving (not heavy city type, but not Interstate) Used to get about 24 mpg city and 27 mpg road driving on a 2008 model, also AWD. Is there a method, adjustment, computer setting or other 'fix' for this that will improve the overall mileage? Have tried both mid-range and high octane fuels with no noticeable difference or improvement. I there an acceptable after-market product that would be beneficial? Thanks for the review.