[basjoos]

There'd be a lot less windshield washer fluid being used (with streamlined vehicles, most of the bugs are swept right on past rather than impacting on the windshield and front of the car and there is no recirculating eddy behind the vehicle to coat the rear glass with dirt).

There'd be less use of the windshield wipers (while moving, most of the rain and snow are swept past the vehicle in the air stream).

It would be safer and you would have much better visibility while driving in traffic on wet, snowy, or dusty roads (low Cd vehicles leave a very minimal trail of airborne water, salt spray, dry snow, or dust in the air behind them). None of this barely seeing the semi through the thick trail of water spray it leaves behind it or trying to clear the salt spray off your windshield in subfreezing temperatures without your washer fluid adding to the frozen mess on your windshield.

If your engine dies on a fairly flat road at interstate speeds, you'll have several minutes of coasting time to decide what you want to do and where along the road you want to finally come to a stop.

Fewer birds and bugs would be joining the legion of road kill along the sides of the road (almost all of them are swept past the vehicle in the air stream).

It would take longer for normal traffic activity to sweep the fallen leaves, dry snow, and lightweight litter from the pavement.

It would be more comfortable for pedestrians and bicyclists sharing the sidewalk, shoulder, and roadway (low Cd vehicles don't produce that sudden shock wave of violently displaced air as they drive past).