Finally had Prius show it’s stuff.

[broski499]

I haven’t yet. It was a super hot summer so I didn’t even consider it. Today was cooler, 85, but I’m guessing that with how short my commute is overheating isn’t going to be a big deal, will just help my engine warm up faster which is what I want.

I will definitely look into this!

You recommending the upper grill portion, or the lower area where the fog lights are?

Could prob work up a front air dam.

[ThermionicScott]

I think the general consensus is to block the upper grille first. For most cars, that seems to give more of an aerodynamic and warm-up bang for the buck than blocking the lower grille, although I'm not sure if that holds for the Prius.

Big +1 to vskid3's post: rather than overheating, it might be that blocking the grille could allow the system to shift into electric mode sooner. Just keep an eye on the coolant temp.

[JSH]

I left the top grill open and blocked the center of the lower grill. If I remember correctly there are 5 rows on the bottom. I left the top and bottom rows open so air could get to all parts of the radiator. I just used strips of black Duct tape and left in on all year. (This was when I lived in Alabama with summer temperatures routinely in the 90’s.)