What we have here are two SUVs from BMW with some differences, such as the starting price, horsepower, and fuel economy. First of all, there is a $38,100 difference in the base MSRP. The 2015 BMW X5 M has a higher starting price than the 2016 BMW X6. And finally, the 2015 X5 M has a more powerful engine than the 2016 X6, and it gets 3.3 fewer miles on a gallon of fuel. Among similarities are the body structure, market segment, ground shadow size, height, and maximum occupancy.