I work on a block with service drives on either side of the thru street. The parking rules dictate that vehicles pull in, generally on a slight angle (though the street in not lined) giving one so inclined full, un-obstructive views of vehicles grilles. The other day I was so inclined. Don't ask me why, I do not know why.
There were a variety of makes and models parked along a 2 block stretch (the extent of my research parameter) and I noticed that styling for grilles mostly alternated between a boxy rectangle with vertical grid lines, as if to suggest open-mouthed teeth bared in a grimace. Like so:

Or a kind of trapezoidal took with the corners pointed up in a mock metal smile. Depending on the sharpness of the angles, the smile could appear friendly or sinister, such as:

