Until relatively recently in Europe, “buy a new diesel car and help reduce CO2”, was accepted by most governments as a responsible piece of advice. In simple terms a late level Euro-6 diesel emits far less CO2 than a gasoline car. But the message is fading amid facts, figures and scares about the dangerous effects of NOx and PM (particulate matter), so diesel, once a “dirty” word that became clean, is once again a dirty word.
 
As governments about-face, confusion reigns and diesel sales across Europe have dropped, with concerns also about residual values. So showroom sales staff offering the latest C-Class Mercedes-Benz C220d AMG Line Cabriolet powered by the company’s OM654, 4-cylinder 2.0-L 143-kW (192-hp) diesel, might be thought to be concerned about their commission. But Mercedes has indicated its continuing confidence in diesel, albeit increasingly in hybrid configuration.
 
Without going into the whole for-and-against emissions arguments, the fact remains that its CO₂ emissions are a relatively modest 136 g/km (NEDC2), meeting Euro 6-d Temp requirements with AdBlue helping keep NOx down. Further interesting figures include a combined fuel consumption (WLTP) of 4.8L/100km, 400 N·m (295 lb·ft) from 1600 rpm through 2800 rpm, a 0-100 km/h time of 7.5 seconds and top speed of 233 km/h (145 mph). To match, handling is taut and torsional rigidity very acceptable.
 
Sampling a soft top diesel in winter may seem a little unusual but it’s an effective reality check; in northern Europe or the northern U.S., its fabric roof is going to be up for a majority of driven miles. In that snug mode there is some diesel rattle transmitted into the cabin when the engine is pulling at low revs. But it is less than that of the previous 2.1-L engine, and in cruise mode any diesel noise is only noticeable by its absence.
 
For sunny cold mornings with roof lowered, the 220d proved quiet and quick, its occupants enjoying Merc’s effective Air Scarf vents enthusiastically blowing warm air from the front seat headrests. That showroom sales commission should not be in jeopardy. Continue reading »