prettiest oem grillblock i know is on the audi A1
it's in fact not really a grillblock as i believe it's an inspection hatch (the hood is not hinged, but detatches, but things like window washers can be accessed trough the hatch i've heared) no versions of the car had an this open, although later versions of the car had a horizontally ribbed panne in place although it was still a solid pannel.
it looked a bit like another grill block as seen on the citroen C2
but it gives the car a visual "gille" without any aero damage, plus gloss black is very fashionable thanx to appels i-whatever so perhaps more carmakers should have a look at it
the car had a 0.25Cd btw