Neither is faultless - they both have the windshield farther forward than it required for good aero, and neither one has any hint of wheel strakes. Things like pillar locations though can be changed without messing up the overall design, though.
The C10 has the narrowed rear wheel track making it lower drag (since the sides can taper), and it has a longer wheelbase; making it more stable, all else being equal.
Here's my second attempt at modeling Sven7's Linner Strømlinet Vogn design, that doesn't have the overly bulbous windshield and kind of splits the difference of the M1000 and the C10 - and doesn't need to be a "cab over" driver's seat: