it's good to see production more cars employing grille blocks, but i don't think all that's pictured are actially real grillblocks, but in some cases "fake grilles" what i mean is that most cars have a strucural support behind the bumper wich leads to the traditional design of an upper and lower grille. some yeas ago audi's upper and lower grille started to form a single shape
and the next facelift/redesign in 2004 the crome trim gave the appearance of a single shape.
this gave the impression of a big bold grille and so other manifacturers started to design bolder grilles, ofen using the same "trick".
like the evo lancer x in 2005
this sort of design is good, because you sepparate the visual "grille" from the phisical cooling intake, but imho, it's not really a grillblock.
same goes for the chevy volt i think, it's a fake grille rather than a grille block.
i don't mean to nitpick but i think it's important to have a close look at whats just design and what's really meant to be functional when using production grilles as a reference
another intersting oem aero trick is what you could call a "side spoiler"
i device to sepparate the airflow cleanly of a rounded C pillar
the renauly espace has it (look for the ridges on the rear window)
the opel insignia sports tourer
and i've also seen it on some new mini's
something very difficult to spot in pictures but intersting are side spoilers on the taillights.
(note the ridge halfway the light)
more and more cars start to use these, they're essentially small spoilers molded into the clear plastic of the taillights, where the overall design has a rounded shape but the spoilers once again gives a clean sepparation..
the senic has them as well as some recent mercedeses...
what's mostely interesting with this mod is that it's relatively small but it's impact must be large enough for carmakers to bother to put it there, and this would sugest that adding small strips to "sharpen" rounded edges at the back could be a fairly simple but effective stealthy aeromod.