If you are convenient to a Sears Automotive store:

I went with a Sears Die-Hard AGM (sealed cells) for my W211. Sears puts them on-sale off and on on-line every few days, so watch for an ad special on your car's application, pay for it on-line via credit card - then go to the Sears Automotive Store with your confirmation number you got from the Sears 800 number, and pick it up from them for the nice discount ONLY available buying online. Then bring 'em your old battery. A lot less than buying the Mercedes-Benz OEM from the dealer - even with a discount, Sears was way less.

Interstate Battery is excellent, but they're in the same price range or thereabouts as the MB dealer, or higher.

On my 06 E320 CDI, it lost no information on the electronics, radio, etc. However this may have been because there is an auxiliary battery on the SBC (SensonicBrakesSystem) year model W211s.

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'06 E320 CDI
'17 Corvette Stingray Vert