Sales of propane autogas-fueled vehicles increased 8% to 14,000 in 2016 compared to the year before, according to data from the Propane Education and Research Council.

The council measured sales of light-, medium- and heavy-duty vehicles, including OEM dedicated and aftermarket conversions.

Over the past four years, the total number of propane autogas vehicles on the road has grown by more than 35%. As of 2016, there are nearly 200,000 vehicles now being used in U.S. private and public fleets, according to the council.

In 2016, about 67% of propane autogas vehicle sales were aftermarket conversions, compared with 33% for OEM dedicated vehicles. Light-duty vehicles also made up a majority of sales at 62% compared with medium- and heavy-duty models, which combined to make up the other 38%.

Forecasts from PERC show continued growth for propane autogas in the public and private fleet markets. By 2020, another 79,900 propane autogas vehicles are expected to be added to U.S. roadways, according to PERC.