Dirty diesel engines are the least of these SUVs problems.
Volkswagen is recalling 800,000 Touaregs and Porsche Cayenne SUVs worldwide but not because of dirty diesel engines. Rather the worldwide recall was initiated due to a securing clip on the brake pedal hinge that could fall out of place. If the loose pin does indeed dislodge it could cause the pedal pivot pin to move. The end result, over time, is that the brake pedal hinge could fracture. In that case the brakes wouldn't work. While the worldwide recall is almost 1,000,000 cars the impact in the US is relatively light.
A total of 83,000 Cayennes and 46,700 Touaregs (MY 2011-2016) are being recalled in the US. The total split is 391,000 Touaregs and 409,477 Cayennes according to Reuters. Now VW says this is a precautionary measure as no incidents have been reported stateside. However, the company did say that "single events have been reported overseas." VW needs all the good press it can get nowadays. Recalls for potentially broken brake pedals don't qualify as good news. That being said this recall is a drop in the bucket compared to the diesel engine recall that's (potentially) to come. That's called looking at the glass half full.