SCOTTSDALE, Ariz. — The zero-emissions Class 8 models Nikola Motor Co. designed and is preparing to build reflect more than just a go-it-alone attitude by an entrepreneur with a vision of trucking’s clean future and the necessary infrastructure to support the trucks.

The U.S. average retail price of diesel climbed 2.9 cents to $3.147 a gallon, and crude oil prices pushed past $65 a barrel to post a six-month high, the Department of Energy reported April 22.

SCOTTSDALE, Ariz. — Nikola Motor Co. CEO Trevor Milton, 28 months after unveiling a prototype Class 8 sleeper, presented to about 2,000 attendees and a global audience watching online two heavy-duty trucks and three other specialty vehicles he said are ready to spark a zero-emissions future.

U.S. trailer orders in March slipped to the lowest level in nearly two years, landing in the 15,000-units range, ACT Research reported.

U.S. Class 8 retail sales in March climbed above 22,000 for the first time this year, WardsAuto.com reported. All truck makers but one notched gains.

U.S. sales of medium-duty trucks in March held steady, settling above 21,000, WardsAuto.com reported.

Condition-based maintenance is coming to commercial vehicles, and bringing with it transformative possibilities to expand real-time operational insights, foster an improved warranty process and, perhaps, accelerate sales of replacement parts, experts said.

To be able to sell trailers in California beginning Jan. 1, trailer makers must certify the equipment meets the state’s greenhouse gas emission standard and be approved by the state’s Air Resources Board.

North American Class 8 orders in March fell sharply compared with a year earlier amid continuing, but slower, economic and freight growth, and a heavy backlog, analysts said.

The U.S. retail diesel average price dipped 0.2 cent to $3.078 a gallon, the Department of Energy reported, as the price of crude oil surged past $61 a barrel amid tighter supplies.