RTH,
My personal experience with these two cars with regard to reliability is in my sig

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The V8 cars, however, should come with an addiction warning. As I came closer to the time to get out of the '94, I drove several cars as potential replacements. None satisfied. I came to realize that having all of that power under my right foot had changed the way I drive and that other cars would not allow it.
So now, I think that I am doomed to drive V8 Mercedes cars for the rest of my life. I guess there are worse fates

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A couple of weeks ago, I had to drive my wife's Saturn. I started down an on-ramp and saw that, in order to merge, I needed some more speed. I found that when I engaged the kickdown, it didn't get faster, just louder

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I have great respect for the 6cyl. version but the 4.2L E-Class car is the bomb IMHO.
Best Regards,