Updating the D exterior design is very difficult. The D was designed at a time when the "square look" was in. (rather than the curved aerodynamic look of most cars today.)
What this means is that the D was/is not aerodynamic as cars are today. Ironically, the "squared off" from end of the cars from the late 70s and 80s was based on an error in fuel economy measurements.
GM was doing a fuel economy test on their cars early 70s (24hrs per day, for months around a track). The cars would get dirty from bugs, so one of the drivers decided to put a bug deflector on the front end and surprise! It got BETTER fuel economy than the other test vehicles. (this was repeated and verified.)
So the "squared off" front end because a design criteria for a few years, until better testing was done.
So we are dealing with updating a car, while maintaining the "square" look. What the design team did was very good. It does look more modern, but there is no improvement in aerodynamics. This would only occur with a rounded edge on the front fascia. or a more protruding front bumper to allow for a longer radiused front end. You can see this design concept on early 80s sport cars.
OR
How about a Dodge "super bird" option? definitely improved aerodynamics and coolness!
Can someone do this up in photoshop? It would, at least be fun to see!