At the recent Sustainable Internal Combustion Engine Symposium orchestrated by the Engine + Powertrain Technology magazine, several approaches for meeting future emissions requirements were brought to light. While engine manufacturers (namely Cummins) believe the current crop of diesel powertrains can meet the 2027 EPA Phase 2 greenhouse gas standard of 0.2 g/bhp-hr NOx without further technological advancements, further reductions will have to be met using a different approach. Among the post-2027 emissions technologies discussed were: cylinder deactivation and advanced aftertreatment systems which would include dual SCR dosing systems, hybridization, multi-temperature cooling circuits, and even variable compression ratio engine concepts.Source: https://dieselnet.com/news/2021/02icengine.php