Hi newbie here. I get 36mpg driving 70 mph here in northern ca on I-5 . 20 miles one way totally flat no grades. I run the tires at spec and use the 5w20 semi synthetic that came in it since day one. Now that the warranty is gone I might try a 0w20.I do notice for every 5mph slower I drive the mpg go up. Unfortunately the motoring public doesn't want to drive as slow as I do.