My 2015 e350
I tend to start driving at the 10 and 2 positions but later relax and drop my arms at some point on longer drives, when I grab the bottom sections of the wheel at about the 8 and 4 positions. The round wheel might be more comfortable for me, otherwise my hands might catch the sharper corners on the lower section of the flat wheel. That's just a guess because I never got to drive a car with the flat bottomed wheel.
Enjoy your ride!







