rjnonnie has it right
Any Mercedes that iswell taken care of will outlast any other. Although there some exceptions to this. 1990 350SD Turbodiesel- The Most UNReliable Mercedes. I would vouch for the 240D to be the most reliable, although I would argue that if one were to drive a 16V the way they drove their 240D (like mary poppins) rather than punching it around every corner the 16V may be one of the most reliable cars Mercedes ever built. Also making the 16V the most reliable gas car with proper care of course.
211,249 and as fast as the first 2.
1986 Euro Black Metallic 190E 2.3 16V