Fleets continue to encounter challenges dealing with aftertreatment technologies that are now being refined after major changes in years past. From a maintenance perspective, aftertreatment systems are improving.

DENVER — The Trump administration is rolling back some U.S. regulations on climate-changing methane pollution, calling them expensive and burdensome, but Colorado says its rules are working — and they have industry support.

The Trump administration’s plan to ease vehicle-emission mandates lifts some burdens for automakers but also would strip away options that have made it easier for them to comply and have encouraged the development of electric cars.

The Trump administration will seek to revoke California’s authority to regulate automobile greenhouse gas emissions — including its mandate for electric car sales — in a proposed revision of Obama-era standards, according to three people familiar with the plan.

Talks between the U.S. and California on auto emissions standards have made little progress since President Donald Trump told his agencies to pursue a deal, according to a top state official, who’s holding out hope that the Environmental Protection Agency will get more involved.

A surge in demand is coming for diesel and related fuels as shipping companies close in on a deadline to reduce sulfur emissions.

Daimler Trucks, Renault Trucks, Scania AB, and other heavy vehicle manufacturers must calculate and report the carbon dioxide emissions of their new models starting Jan. 1, 2019.

FLAT ROCK, Mich. — Executives with the North American arm of engineering company Robert Bosch showed off an electric-hydraulic steering system for Class 8 trucks that they said will aid in the transition to autonomous commercial vehicles and announced a “breakthrough” in substantially reducing emissions of nitrogen oxide from diesel.

Lawsuits over EPA’s April fuel economy determination are more than just a pre-emptive strike, challengers say: They’re an effort to force the agency to consider thousands of pages of its own data as it considers weakening emissions limits for passenger cars.

A group representing the vast majority of the world’s ship owners said world trade is at risk if issues surrounding new fuel rules aren’t resolved quickly, providing the starkest warning yet as to the potential impact of regulations that are due to enter into force in less than two years’ time.