W124 water leak from road spray

[Legoinsaniac]

I'm having trouble tracking down a leak in my 400E. After a long drive in the rain a few weeks ago, the driver's side floor mats (front and rear) became SOAKED with water. I pulled them out, dried them out, and left them out in hopes I could more easily see where the water was coming from. The water doesn't get in when the car is just parked. It's rained heavily since then, and the floors remain dry. So I assume it's coming from the road spray while moving. I drove again in the rain this morning, and sure enough, much more water in the floors. Probably half a liter in a 20 minute drive. Where could this be getting in? My sunroof drains are clean and flow normally. My door seals are also fine and show no evidence of leaking. The water must be getting in from somewhere under the car, from road spray. But where? Any similar experiences?