The 300se I currently drive is also affected by crosswinds.
Initially, I thought it could have been the springs, struts, etc ... and had them all changed. It still didnt work when I cruise at about 160 - 180 km/p. So, I tightened the steering, and realigned/balance the tyres, and there was "a little" improvement.
I then read the threads here and decided it is quite normal. However, at around 120 km/p the wind gush by the drivers' side window gets a little distracting (unless the audio system is pumped up to drown the noise). That, I have aligned and changed all the rubber linings - and it improved. Though not much.
However, compared to other non-MB cars at 160 km/p the 300se fares much better. Perhaps we MD drivers are a demanding and fussy lot. I know I am.