Behold I may have possible solutions for your ills - especially if you park nose up
I've had my 159 3.2 Q4 for 4 weeks and at first I noticed the water getting onto the door seals. Investigation showed that a small amount water was getting past the door inner panels on the LH side only. Unlike all other cars I've owned, where a plastic membrane is glued (or otherwise attached), the inner panels are steel pressings and they have a gasket around the outer periphery.
On mine there was some seepage along the bottom edges of those panels. This was fixed as follows:
Remove the panel retaining screws along the bottom and the sides. Loosen the top edge screws. Now the panel can be pulled away from the door at the bottom so that sealant can be applied to the gasket. I used Hylomar non setting material. After I re-fitted the screws I then applied a bead of Silicone sealant around the inner door panel. So far there have been no leaks from the door areas.
However, it was while investigating the door leaks (car parked nose up) that I found a significant other leak where the RH rear carpets were sodden and there was water visible through the chassis number inspection flap at the front
I completely removed the carpets (seats out etc.) so that they could be allowed to drip dry in the garage. The 'undercarpet' is sponge rubber and it acts like a sponge, funnily enough.
I found that the source of the water was from a badly sealed seam between the scuttle and the A-Post at the RH side.
The picture shows this area - you have to remove a bit of sound deadening stuff to see that BTW.
Although I could have done this myself, the car has gone back to the dealer to have this fixed. I'll let you know the outcome but I'm 99% sure that that's the only place.
(The car is also having a new TEG unit (ignition switch) because it had the 'cold weather remote locking failure' problem too).
BTW the car did not leak when parked in a nose down position. Don't know what the situation would have been in a horizontal position but I suspect it would have leaked in deluge conditions.