I sold my W203 at 11 years old with the original MB-branded Varta battery still going strong. My W204 was sold at 9 years old, again with the original MB/Varta battery, and ECO stop/start still working. There are exceptions, obviously, but in general it seems that these MB/Varta batteries can last a very long time. I just wonder if the Varta and Bosch batteries manufactured as after-market replacement parts are of the same quality as those they make for MB? On second thought, it probably doesn't matter because if you buy a new replacement battery with 3 or 5 years warranty, it will last through your ownership of the car, so not sure if it makes sense to by a genuine MB battery (i.e. manufactured for MB by Varta) even if it was true that they last longer - most people won't need a battery that will be good for another 10+ years on a second hand car anyway.
