Lectrofuel is correct, the nomeclature I used apparently was only adopted in 2017 when the SLK was changed to the SLC (SL means apparentlySportlich Leicht (German for "Sport Lightweight")). Sorry for the wrong information.
C class car 2001 to 2018
2002 - Average overall. Minor Engine problems, minor transmision problems, body integrity problems, body hardware problems, power equipment problems, in car electroinc problems.
2003 - Average overall. Major engine problems, minor transmisson problems, climate system issues, suspension issues, power equipment concerns
2004 - Average overall . Minor transmission problems, fuel system problems, paint and trim issues, in car electronic issues
2005 - Above average overall (rare in Mercedes). Minor transmission issues, Climate system problems, in car electronic issues - but that is it.
2006 and 2007 - average overall, but they have a higher number of engine and transmission issues and other problems as well. I would avoid.
2008 - redesign year and surprisingly a good year - above average overall. Minor engine problems, paint and trim, power equipment, and in car electronics are problem areas.
2009 and 2010 - average overall. Problems with major engine, body intergrity, and power systems.
2011 - way above average overall. Just a problem with in car electronics - that is it. Best year of the bunch.
2012 and 2013 - average overall. Engine problems return, Power equipment problems, and body integrity issues.
2014 - Great year, way above average. No problems to report in Consumer Reports.
2015 and on - redesign in 2015 brought on a bunch of changes and major issues ranging from major engine problems, minor transmission issues, body integrity, power equipment, and in car electronic issues.
So best years are 2011 and 2014, and 2005 is not bad either and just a little worse is 2008. After that you probably take your chances. Again, this is the C class which Lectrofuel wisely corrected me on.