I am noticing intermittent instances of water on the passenger side floor board. Symptoms are very similar to what I've seen with clogged sunroof drains, but I do not have a sunroof. I have a convertible. And I don't think it is caused by rain. I think it happens just after automatic car washes.

Besides the sunroof drain leaks, are there any other common culprits for this leak? Other places it could be coming from? Maybe from underneath the car?

 

Someone in the sedan forum (here)mentioned that they thought the water was coming up from underneath the car via the hole where the AC Evaporator drain tube passes. It might not hurt to pull up the carpet and add some silicone to the grommet- though, personally, I am skeptical of that potential source...

Also, you may want to check your cabin air filter for signs of water. The windshield cowl seals have been known to deteriorate and fail allowing water to leak into the cabin via the fresh air duct (located under the cowl). (thread)

 

There are drains in the convertible roof as well. They are built into the gasket on the rear of the mid-roof. But if I was looking for water in the pax side I would first check your window is sealing on the gasket.

 

I was the one that thought I had it coming up from underneath the car via the hole where the AC Evaporator drain tube passes. That tube/grommet were very loose on mine. I've parked the car and letting it dry out so I can put some silicone around that area.

 

I've seen light leaks from the window seals, like @n559br said - definitely check there.
IIRC, there was a method of adjusting the height of the windows, if that's indeed the problem.

 

To add to what Kiseliok and n559br suggested, you may want to look into these threads as well:
Window Seal Leaks
Water Under Carpet

In my case, granted for a 2008 Coupe, water was coming in from the "triangle" mirror seal. I ended up just replacing all of the seals and have, thank goodness, been dry ever since.

Good luck and please let us know how you make out.

 

A very important clue is car washes and not rain.
Car washes equal out to monsoon winds moving masses of water out of your car.
One way to test the theory is pressure washing lightly the vehicle for extended periods or a decent size pressure garden hose targeted to the windshield/ door seal area.

More than likely it's the windshield to top seal however unless you fully dry all of your canals, trims, etc prior to the car wash then opening the top or inspecting rain drips there's not much you can do.

Might want to start looking for handwash services.

 

^^ Touchless carwash is how I figured out all the common leak places..
Since then, I've always washed my car by hand.