Well, sounds like an adventure! Better mpg on the way back? Hope so!
Think I averaged 19mpg in my pre LCI F10 M5 never really saw any better than 28/29, (14 in F430, 23 in M4, 26 in X5M50d and 23 in M3T over first 5000miles).. like your upside down profile pic, reminds me the X5 used to say POS ...