I have just bought a new battery for my 300 sel. After a lot of thought of "should I or should I not" buy a genuine Mercedes battery, I did buy a Mercedes battery. Anyway glad I did. I had a Interstate HD battery that is appx. 28 months old. The replace cost was a $100.00 cdn. The Benz battery was $165.00 cdn. The Benz battery is at least 5 in longer and 1' wider. I don't know but it has been in my experience that in most cases bigger is better. Besides when I open the hood that white battery with the blue star is looking up at me saying "quality" That is why we buy Mercedes in the first place. That battery comes from Germany just like the car. Spend the extra few bucks and get the proper stuff, or buy a domestic car.