[aerohead]

It's virtually impossible to have a laminar boundary layer with a production vehicle driving on the road.
Do to the phenomena of Prandtl's lines of discontinuity and the viscous shearing of air strata,as they are positioned further and further away from the road surface boundary guarantees that the air is fully turbulent before the car ever reaches it.
Only a sole race car,alone on a track with zero wind would ever have a shot at a small amount of laminar boundary layer and that would only last until the windshield area due to the mandatory transition to TBL @ 1st minimum pressure.