You think your car "needs a supercharger?" LOL. Hey, you have a 300E, so enjoy it. Your car will inhale 0-60 in just over eight seconds (faster than mine, which in its modified form will maybe do nine flat...) and has a much more tossable chassis than my W126 autobahn cruiser. Personally, I envy 300E drivers...they've got great machines.
Hey, I've even been able to chase a friend's E30 (BMW) 325i (not an iS) down a twisty road, although with LOTS more body roll than him, but I never found the limits of tire adhesion....thanks to my Bridgestones....
I guess one might feel a little inadequate if one owned a BMW M3 beforehand, but that's the only reason I'd ever think....
"yeah, I think my car could handle a turbo or two with its 8:1 stock CR and new forged pistons..."-me