It's a bit of both but yes velocity dominates the drag forces. You can reduce the wind resistance of vehicles reducing their coefficient of drag but the dominan

It's a bit of both but yes velocity dominates the drag forces. You can reduce the wind resistance of vehicles reducing their coefficient of drag but the dominant factor as you reach higher speeds is velocity which increases as a square where the drag coefficient is only directly proportional to the end drag. There are definitely limits to how low drag we can make the normal passenger sedan without drastically changing it's functional form. If we move to a more infrastructure style car transport where you just subscribe or have access to (depending on where we end up on the public-private spectrum) there's probably a lot of gains we can still make that will make cars much uglier (to our current eyes) but more aerodynamic.