Had a small revelation today. Not all jurisdictions require a front plate and indeed on many vehicles where they do, it's stuck on the front there like it doesn't belong, not a proper "place" for it.
Often it seems it's hanging down and messing up the designed aerodynamics of the lower bumper/airdam area. Now, most vehicles these days feed the rad from down there mostly, and the vestigial upper grille is mostly cosmetic, or required only to let the fan breathe when you're sitting in traffic in summer.
I'd been thinking for a while of making a "windslammer" for the lip of the front bumper to encourage air to miss the upper grille at speed and force more over the hood. It occurred to me today, that on many vehicles, one might get much of that effect by relocating the license plate. Instead of mounting it on 4 holes on the bumper, one could use the top two holes there and the bottom 2 of the plate. Thus sticking it up above the bumper. Then give it a slight rake to aim the air hitting it onto the hood. Might want to make sure you've got good screws and probably some extra washers around the holes to make a good firm mounting for it.
Potential advantages, depending on design...
Cleans up airflow of the stock lower bumper/airdam arrangement.
Pushes air over the hood at highway speeds.
Allows air gap for the fan to "breathe" in situations where extra cooling is needed.
Might help MPG for winter highway driving by the effect on reducing excessive cooling.
Could save you parking hassles if you have a low slung one and are always catching it on curbs and those concrete divider things they use in parking lots.
Don't know if you'd get measurable MPG gains from doing this, but there might be some vehicles where it would be worth +1mpg highway on the aerodynamics and some it might be worth another 1 or 2 in winter.
If you find out it works awesomely well, and have a wide grille, I guess you could try flanking it each side with an ornamental "plate", you'd need to drill holes for those though. If you don't "need" a front plate, but hear of improvements on your model of vehicle, you could try an ornamental one in that position.
Just another of those stupid little things that might add up to a dollar or two more in your pocket each year...