automatic electric grill blocking

Wouldn't it be easier to have two sheets of plastic layered together with slots cut in them and just slide one of the sheets up or down so that the slots are out of alignment and it would block any air from flowing through, then move it back and the slots line up allowing air through again. A lot less complicated then louvers or blinds I think.

 

Yes, much less complicated, but you are still blocking over 50% of the grill even when fully open. Might work for climates that don't get real hot in the summer (Alaska, Canada, Washington & Oregon west of the Cascades). Plus, they're probably more prone than louvers to sticking due to road dirt between the sheets.

 

I think the exterior temp would be the best answer.
To get fancy, make them open if the car gets close to overheating.

You want to keep the ICE warm (That sounds wrong) to allow it to shut down while driving.

At highway speeds, having it open would probably be a good idea to prevent it from overheating.