I don't own an X, but it is well established that it's Wh/m efficiency is significantly less than the S. Many S owners average just over 300 Wh/m. Your Average Energy numbers seem a bit higher than what I have seen other X owners post. How fast do you typically go on the freeway? (When traffic isn't slowing you down.) Going 75-80mph is going to produce much worse efficiency than going 65-70.How does my efficiency look, good/bad?