Another question about candy-loving mice in car: What about extractors?
Dear Car Talk: Someone wrote to you recently about some mice that got into his car and selectively ate his peanut M&Ms. He wanted to know how they got in.
You said the only way into the passenger compartment is through the cowl, where fresh air comes in below the windshield. Couldn’t they have gotten in through the “air extractors” under the rear bumper? — Michael
Michael: I’d never heard of air extractors behind the rear bumper before, Michael. So after I read your letter, I moseyed next door to my friend Leo DeLeo’s autobody shop and asked him.
“Oh, sure,” he said. “I’ll show you.” He takes me over to an older car in his shop with its bumper removed and points to the back corners under where the bumper had been. And lo behold, there are two small sets of flaps!
They have several purposes. Primarily, they release air from the car when you close the doors, so you don’t build up too much pressure. Modern
cars are well-sealed — for noise reduction, comfort and fuel economy — and that means there’s no easy way for air inside the car to escape.
So, if you get in the car and pull the door closed and the air pressure goes up, that can be uncomfortable for, say, your ears, like when you’re in an airplane. It can also make it hard to close the door or make it hard to close the door easily.
In fact, some years ago, BMW had a system that automatically lowered the window a skosh as you closed the door, and then immediately closed the window again once the door was shut. I assume that was another way to address the air pressure.
The other purpose of these flaps is to increase the flow of fresh air through the vehicle.