Under most operating conditions, the engine exhaust is hot enough to oxidize soot via a passive regeneration process. However, if conditions call for supplemental regeneration, the Cat Regeneration System is designed to work transparently, operating automatically without any interaction from the operator and regenerating when conditions are optimal.
One Question Left Unanswered
Based on the comments from engine manufacturers, there will be no degradation in engine performance with Tier 4 Final solutions. Fuel economy will be similar or improve, depending on the particular engine make and model.
That said, you may now have another fluid (DEF) to purchase and maintain. In addition, while many engine suppliers were unwilling to share information on pricing at this time, it takes more resources to design and develop the additional components required. Time will tell how much of the cost may be passed on to off-road equipment manufacturers and, ultimately, the end users.