Just towed the M6 home (6000# total weight with trailer & car) to Wisconsin with the 2011 diesel. 952 miles and averaged 17.2 MPG running mostly at 74 MPH. At 70 MPH it was running at 2000 RPM. It did seem effortless and I was very surprised at how well the towing went. I'm guessing there is no way a gas X5 would get close to the same MPG's.

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Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out and loudly proclaiming: "WOW! WHAT A RIDE!!"

2007 M6
2018 Chevy 2500HD Diesel Alaskan Edition
2011 X5 35d
1972 Chevy K20 4X4
1972 Ford F-600
1959 Chevy Viking 60 Dump Truck
2015 CanAm Outlander XT 1000