Thanks.
The top row of openings are actually closed at the factory and allow no air to pass. So I have only 1 row letting air in plus the "crack" where the hood and bumper meet.
The top 2 rows are open on the bottom grill.
The openings are very easily adjustable with another piece of tape or removing one.
I have also closed off the fake brake cooling ducts with 3 pieces of tape. Again all in an effort to smooth out the airflow.
I have not had a previous clean run of some distance at 70 to be able to do a before and after calculation. Previous record high 41.48 mpg Canadian on the back highways at about 55 to 60mph.
Exceeding the Highway EPA estimates at 70 mph pleases me and is something of an accomplishment.