Sales of light-duty vehicles equipped with diesel engines crossed 500,000 in 2018 partly driven by a 12.5% gain among heavy-duty pickups, according to a leading diesel advocacy group.

"Available diesel options continue to grow in America’s top selling vehicles: full-size pickup trucks," said Allen Schaeffer, executive director of the Diesel Technology Forum. "Recent announcements from General Motors, Ram, and Ford signal this is a trend that will continue through 2020 and beyond."

Fiat Chrysler's Ram brand added a second diesel engine option to its 2019 Ram 2500/3500 pickups — a high-output 6.7.0L Cummins inline-six turbodiesel — the company announced at the Detroit auto show. General Motors added a new Duramax 3.0L turbo-diesel engine to its 2019 Silverado, while the 2019 Ford Transit Connect offered a 1.5L EcoBlue turbocharged four-cylinder diesel for the first time.

For light-duty vehicles in Class 1 through Class 3, sales of diesel-equipped models reached more than 500,000 units in 2018, which represented more than 3% of the overall market of 17.33 million vehicles sold. More diesel vehicles were sold than gasoline-electric hybrids or plug-in electric vehicles, which each represented about 2% of total sales, according to the group, which sourced Baum & Assoc. data.

Class 2 and Class 3 pickups have been driving the growth with a 12.5% growth rate over 2017. Non-annualized growth over a three-year period has reached 35%, according to the Diesel Technology Forum.

Diesel sales of smaller vehicles increased 9% in 2018 following a decline in 2016 and 2017.

More than 40 diesel models are available in the U.S. from 10 manufacturers and brands. New diesel engines will also be offered in the 2020 Jeep Gladiator midsize pickup, 2019 Chevrolet Silverado 2500/3500, and Mazda3.