[Otto]

One reason for reduced drag is the location of the foglights: Consider one of those color-coded pressure graphics showing air pressure along a car body, where red is the highest pressure, and blue the lowest. These correspond to the airflow velocity. So, the nose stagnation point is biright red, since the air flow slows and is compressed there, but as the air then accelerates rapidly around the fender and up over the leading edge of the nose, the map shows bright blue.

The air flowing past your lower nose section pretty much stops at the centerline stagnation point, then accelerates but stumbles as it goes past the fog light bay irregularities.

This is a terrible place for any flow disrupters to be, as the airflow there tries to be very fast. Doubling the speed of the flow means 8X the drag, so you want to avoid any shape irregularities in such drag-prone locations. When you covered your foglights, you pretty much fixed the OEM bad shape there. It's a pity the factory designers don't "get it." They should never have botched this shape in the first place.

This reminds me of a conversation I had with a NASA aerodynamicist: He pointed out that on airliners, flashing light fixtures were often put just above the cockpit windscreen, right where the curved shape blends into the tubular fuselage. He said that is the worst place to put a bump for the flashing light, because just there the airflow exceeds the forward speed of the plane. In other words, if the plane is flying at 450 knots, the airflow accerating past the nose if going significantly faster than 450 knots at that particular location, and since drag increases exponentially (2X speed = 8X drag), the drag penalty is very high. Better to put the strobe lights someplace else, such as at the very tip of the nose at the stagnation point.

Not to hijack your thread, but I posted another thread about optimum nose shapes, Hucho's latest findings, etc. This because I'd like to do a nose on my Porsche that (like your modded vehicle) has nice optimally smooth shape, i.e., no fog light holes in the wrong places, etc. Your mods reinforce my hunch that nose shape is very important not just to reduce drag at the nose, but also to smoothe the airflow for as non-tubulent and optimum flow along the body as possible. So, thanks for sharing.

PS: One cheap and easy way to fill these holes would be to put aluminum foil into the nooks and crannies, held in place with tape. Smooth the foil to the body, then fill the foil-lined cavities with Great Stuff expanding foam, let it rise and cure, then sand to match the body contour, then spray with PlastiDip or paint to match the vehicle. With the aluminum foil prophilactic barrier, the foam will not stick to the car, so you can pull it off without a trace.