HC= hydrocarbons thats what gasoline is made of. If your engine is emitting too much HC it has a miss or some other problem that is preventing all of the fuel from being burnt. In the above example the engine was running too rich. I can tell this because your CO was at 8%. CO or "carbon monoxide" is tied to fuel mixture the richer the engine runs the more CO. The O2 sensor or "exhaust gas oxygen sensor" on you car will attempt to keep the CO level at around .7% Some will run a little richer some a little leaner depending on the engine and temp of the sensor. NOx nitrogen oxides are a result of heat and pressure in the combustion chamber the greater the combustion temp or heat the higher the NOx. The reason the NOx was so low because you had too much fuel resulting in incomplete combustion and thats where your HC came from.
It's true that cat convertors reduce all of the things (provided it's a 3 way) they should not be high in the first place and to adjust your engine with a gas analyser you have to measure in front of the convertor, most euro cars have a provision for this. Something must be wrong with that car if it was running at 8% CO even if it was cold. That much unburnt fuel and CO will ruin that cat and I bet they are expensive on a benz. P.S. I am an ex Canuck pm me please tino