Hi Ernie,
Over sixty years after the P-51, I've yet to see extensive laminar flow on commercial aircraft, let alone production cars. So, you might want to start a separate study on what might be achieved, after we get the rest of the shapes right.
Perhaps the biggest area for improvement in North America is reducing wasted capacity. As I recall, it is hard to see around in traffic in your neighborhood from a small car, because of all the big, empty trucks. There are huge problems of perceived safety and status. However, we can remind folks that "John Wayne hauled his manhood around with only 1 HP."
Anyway, assuming that people will achieve enlightened self-interest regarding vehicles, we could encourage driver's co-ops to let people drive tiny cars and still have a big one available on occasion.
Personally, I'm sketching a cabinscooter that can take on a single adult passenger, bobsled-style, or the usual kids and groceries load. Occasional overloads would go on fold-down platforms beside the single rear wheel, on on a trailer. The driver's seat would recline, to allow sleeping over instead of some return trips.
See
What is a Hypercar® Vehicle? for the hypercar project, too.