Local delivery fleets with stop-and-go service had improvements as high as 12% in several cases, the company said. Long-haul and mixed service fleets had gains of 4-7%.

"These tests demonstrate that our additive brings important benefits not only in the control of diesel engine emissions, but also for fuel economy improvement," said Clean Diesel Technologies COO James M. Valentine. "In short, this additive catalytically promotes better engine combustion."

A total of seven separate fleets were involved in the field testing, which were conducted over the last 18 months. More than 200 trucks took part in the tests, which extended to more than 8-million miles of commercial highway service.

Platinum Plus is a patented formulation of fuel soluble platinum and cerium catalysts that Clean Diesel Technologies says improves the rate and completeness of combustion in the engine. The product is added directly to the fuel by the truck owner.