Look at the 1989 Civic hatchback in comparison.
I gotta go Google the coefficients of friction for both these cars.
Edit: It looks like my comparison is not fair because the Mazda 6 appears to be a four door coupe and this civic is a 2 door hatchback. Also exhaustive lists showing coefficients of friction are hard to find.
Edit #2: A fairer comparison is a 1989 Mazda 626. You can see
through this thing:
It has a coefficient of drag of 0.33 while the current Mazda 6 has 0.27. So the more modern one is slightly more aerodynamic, as you would expect, but not significantly more.