Insulate cabin air intake?

When the cabin air is drawn directly from the outside and the car has been in the sun for a while the air coming out of the vents is quite warm. Much warmer than the air outside. The difference feels like at least 10F, perhaps 20F in some instances. That is "hand out the window" versus "hand over the vent" when the car is stopped. Of course it gets very hot under a car's hood, so I wonder where the cabin air intake is located, and if anybody has had success insulating it in order to reduce this unwanted air heating?

The excess heating goes away if the car is driven on the highway, but even then it takes around 5-10 minutes at speed before ambient temperature air comes out of the vents.

This makes me recall one feature of my old '65 Corvair fondly. No A/C, but the under dash vent and moveable quarter glass windows

(see https://en.wikipedia.org/wiki/Quarter_glass)

kept the cabin reasonably cool even when it was quite hot. As long as the car was moving anyway. Some of my female front seat passengers were a little less pleased on occasion with the fully open under dash vent, as it could inflate a skirt or dress like a balloon. It never went fully "Marilyn Monroe on the grate" because they were always sitting on half the material. The motor was in the back so it didn't heat any of that cabin air.

 

Not a lot to work with there.

Only the top row of intake slots is visible from the outside when the hood is closed, and air through those is going to be sucking hot air right off the hood. The much larger set of intake slots under the hood will be pulling in air heated up by passing by the radiator, motor, and so forth. I suppose I could paint the hood and that part of the intake white, but since the car is already silver gray, changing the hood color wouldn't be much of an improvement. Especially since it looks like the majority of the air may be coming in from under the hood. The duct under all of those intakes is hard to see but it appears to go straight back into the dash. That doesn't seem like a promising avenue either. The only thing I can think of that might help would be to somehow route an insulated duct all the way from the front grill through the engine compartment, around and behind the hinge, and into the air inlet under the hood. It might work, but it looks like more likely it won't.

We already use a good window screen when the car is parked, heaven only knows how much hotter the air would be without it.

I don't dwell on Marilyn Monroe, it was just that car really did have great outside air delivery, enough so that I had to warn any female wearing a skirt not to just pull the under dash vent wide open. This was a long, long time ago, in the 1970's.

 

I need to inspect those seals more closely. 15 year old car so any rubber in that location will have been baked every hot day and might have failed. On the other hand, the "outside air" from the vents does cool off eventually so that it is close to the "hand out the window" temperature, at least in highway driving. Hard to guess which would make the area under the hood hotter - baking in the sun or driving the car at 70 MPH. Certainly the wind blowing over/through the car will cool it considerably at that high speed. Well, parts of it. On hot days the windshield glass starts blazing hot and stays that way. Maybe the light metal of the hood cools with a good breeze going over it?

 

There aren't any gaps in mine, but both the top foam rubber and the bottom "tubular" rubber look pretty squished. I'll have to snake a camera in there (when it is cool enough not to heat stroke) and see if there are actually visible gaps between the two. Is the bottom piece supposed to be glued down all the way across? Mine is firmly attached where there is a screw or fastener through it, and in some other regions, but elsewhere I can pick up the rubber with no effort to make a gap under it for the full length of the region between fasteners..

That seal does not go all the way to the passenger side. There is a large hole near the fender where hot air could go right around that rubber air dam.