Flap between trunk sidewall and inner fender...passenger side...what is the purpose?

[Speedmaster]

Am curious about it. I happened to be cleaning out my trunk and found it behind the trunk liner.

Since I don't have my fender liners in, I can see where water could get in.

 

[Bram]

This flap is to allow air to escape from the car when you closed the door or driving with the Windows's closed

 

[JD Cross]

The truck is not connected to the passenger compartment so the trunk vent has nothing to do with closing the passenger compartment doors or driving with passenger compartment windows up or down.

I believe the vent in the trunk is a one way vent to let air pressure out as the trunk space warms up from the exhaust and engine heat and the air in the trunk expands.
Without fender liners I could see road water blowing up to the vent area so one would want to keep an eye on the area if driving in the wet.

 

[Speedmaster]

On a related note...one should NOT touch the metal in the trunk after driving for more than say, the time it takes to warm up the car. Ask me how I learned this. Yep, I rested my palm on bare metal to look inside the trunk. Luckily, it didn't scald me on contact. Just pretty hot.

 

[white98sh]

The flap is there to make the trunk easier to close. Nothing more nothing less.

 

[LJSB]

The flap is there to make the trunk easier to close. Nothing more nothing less.

Yes ^. The technical name for such is a "pressure relief valve".

To the OP:

FYI. You may already be aware but, not having the liners in, the potential for damage to the rear quarters from stone and debris hitting is very likely, especially if you are tracking the car. This damage will range from abrading the inner surface so bare aluminum is exposed to dents from stones, poking outward.

On the driver's side the fuel filler neck is there so keep an eye that it does not get damaged suddenly and go unnoticed.

 

[Speedmaster]

Good call on the liners...I have ordered the grommets/screws to put them back in...

I bought the car with them removed (car was lowered). Now that I have raised the car back up, I can replace them. I am surprised I don't have outlines of road-rocks/debris showing up on the outer skin of the rear quarters already.

On a side note, I noticed an amber to almost brown tube on the driver's side that had been severed and was resting against the rear wheel. It appears to be a fuel runoff tube and I can see where a full-length tube would fit into a clip down near the bottom of the fender. I will replace that as well this weekend.

I have a few projects including putting the rear trunk lid and spoiler on (thanks Shawn, I am finally going to open that box), install LEDs (thanks, Jim) and maybe...maybe, put the new leather seats on (see above).

If my box shows up, I am going to put the liners in, hinges on the engine lid, replace the liner and carpeting in the trunk and who knows what else.

 

[silver2002]

There is also a flap/air pressure relief for the passenger compartment [ to help in the closing doors, since cars are so air tight],
you can see it when the passenger side skirt is off - small and rectangular.