I own an older Mercedes E class as well as an older Acura TL and do my own maintenance. The Acura is cheaper to maintain and they are more responsive with voluntary recalls. The Mercedes parts cost a bit more but also last. I was able to maintain my Mercedes without a factory service manual, since Mercedes didn't make them available to the general public but with the knowledge of Mercedesshop I was able to do without the service manual. If you live in a snowbelt area I would recommend snow tires for the Mercedes since it is rear wheel drive. I prefer the ride of the Mercedes over the Acura but I am also partial to rear wheel drive vehicles.

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Ray
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles