Where I see they got the back right, they really screwed the pooch at the windscreen to roof transition. I know it's heresy to say it, but the front matters, the back can be perfect but if the air is doing cartwheels when it gets there, then the back isn't going to be very effective. It becomes the lipstick on a pig at that point.
Contrast that to the modern best aero MB CLA with a debatable .22 Cd and you see an amazingly gradual transition in this area. Most modern cars with good aero have this characteristic.
