I have a less-than-permanent upper grille block in place. It is made of heavy duty transparent duct tape, and so far it has held up well though a week of rainstorms...
I decided to tape the grille first to see how the temperatures would respond to less airflow, and it has taken well both at lower city speeds and at 55 mph on the highway. So in the future I will replace it with something more permanent, possibly sheet aluminum, or whatever I can get my hands on.
Additionally, I swapped conventional oil for Castrol synthetic 5w30, and also decided to switch to a K&N air filter. And last but definitely not least..
ScanGauge II in place! Arrived just last night. The old Kiwi MPG instrumentation will be given to a hypermiler-in-training