Plug-in electric vehicles (PEVs) have topped a million units sold in 2017, according to a report by Navigant Research.

Recent PEV developments, including the introduction of battery EVs (BEVs) with increased range and a sub $40,000 price point, have helped drive PEV growth in 2017, a summary on Business Wire said.

“Battery costs have shrunk dramatically in the last five years and promise to shrink further with the commercialization of solid-state batteries on the horizon,” says Scott Shepard, senior research analyst with Navigant Research. “In addition, increasing regulatory pressure in Europe and China may well push the PEV market to the aggressive end of the forecast range regardless of oil prices.”

Business Wire predicts a worldwide PEV market with robust near-term growth. The U.S. market is less certain, based on the potential for changes in government policy, including the reduction or removal of subsidies for PEVs.