Removable air dam for bull bars

[Schnaphappy]

Just a thought... Does anyone make removable air dams for bull bars for all the times that we don't go 4x4ing or travelling to a destination along a highway.
I've just been hearing how important the air dams are on new cars and how efficient it makes them when driving at highway speeds as it help with the airflow around the car.
So why can't we have detachable ones?

 

[happy john]

Probably would have something to do with injuries sustained by a pedestrian in the event of an accident, that seems most logical I doubt any company even makes one besides the aerodynamics of our 2.5 tonne bricks is poor to begin with.