I will, in a way, take issue with the claims of the 124 with 103 being the most long lived Benz ever made. I would correct that to say it is the longest lived GASOLINE ENGINED Benz ever made. The 123 diesels MUST be the longest lived.
I do understand the sales managers comments. Although I did have to do cylinder head work, my M103 engined 300E is at 196,000 miles now and has never been stronger. They are incredibly well built cars. They do have their achilles heels, the a/c and the valve seals, and a few minor weaknesses. But, keep in mind that these cars are definitely longer lasting cars than most anything else out there. If they last longer, there is more time and more opportunty for such things to be reported.