Bumping on and off the drive makes the car creek and groan like crazy. It must be a pretty flexible body shell. No other car I've owned has done this
I'd echo that statement.
This post had got me thinking though so when i cleaned it the other day, i use an ordinary can of spray silicone with a straw and sprayed it into and all around the grooves on the seals, then wiped off any excess making sure the whole seal got coated.
It is way better i've lost about 75% of the noise, there is still some, but i no longer wonder if the car is a Cut and shut

Well worth a Try IMHO and normal silicone just wipes up easy enough although the seal did seem to soak almost all of it up, i may well try it again soon to see if it gets even better (although most of the noise seems to come from the flex in the tops of the back doors, so is it a 5 door thing?)
Sandy