Had a great example of how rain can affect MPG. A trip from Maine down to Massachusetts yesterday, new full tank, good roads, freeway some attention paid to mileage, arrived at destination with 68 mpg including lots of 70mph, 120 miles covered. The return was mostly in a driving rainstorm, the one that dropped 13 inches on LI. Tank now reads 59.6, same road, mostly running 55 mpg or slower. Much of the time spent under 50 mpg.