Looks like this thread has drifted a little from the original poster. Just to keep everything in perspective, the location of the battery in an E320 is in the engine bay where it is not confined to a closed area; therefore, there is no need for a battery vent tube. And, I think you will be surprised if you shop aftermarket batteries against the MB OEM battery. In my case, the OEM battery is consistently lower cost than a Sears Die Hard!