The ‘clean diesels’ in question are the B4.5, B6.7 (pictured) and L9 engines with a 148bhp to 395bhp range for bus and coach applications.
The Euro VI Phase D engines achieve “nearer-to-zero emissions”, says the manufacturer, representing an incremental step towards Euro VII regulations, anticipated to take effect after 2025.
Cummins says tests have shown the latest engines can deliver a 25% reduction in NOx emissions compared to the first Euro VI engines introduced in 2015.
“With exceptionally low NOx emissions, our latest Phase D products will help bus fleets improve air quality and align with the recent arrival of the London ultra low emission zone and other clean air zones being established in cities across Europe,” says Ashley Watton, Cummins director for on-highway business Europe.
“Phase D development work required a substantial investment by Cummins, but it does mean our customers retain the benefit of a proven product with identical performance to those they experience today. In terms of vehicle integration, this is no need to re-engineer the Euro VI installations, as our Phase D engines offer a seamless, drop-in solution,” adds Watton.
Cummins is also extending Phase D to the hybrid-adapted versions of the B4.5 and B6.7 engines. It says that when integrated within a diesel-electric driveline, the clean diesels can cut fuel and CO2 emissions by a third.
For conventional diesel bus drivelines, Cummins engines featuring stop-start technology will also move forward to Phase D, saving fuel and greenhouse gas emissions by virtually eliminating engine idling at bus stops.