The po stuck a little 350 or 400cca amp battery in my friends S320.
I would cringe everytime he started it crossing my fingers that it would fire, but it always did. He put an Interstate in it, and I got him a deal at $88. 84 month top of the line, MTP-93 same battery that the W126's use. It is still light compared to the OE MB battery, but seems to crank well.