From 2013 through 2017, US sales of BEVs versus PHEVs were neck and neck with PHEVs actually eking ahead of BEVs in 2016 by a bit more than 700 units. But then the EV world changed with deliveries of the Tesla Model 3 beginning in the US in July 2017, but really kicking into gear in 2018. 

The Model 3 significantly changed the BEV versus PHEV mix with BEVs jumping up to 62.1% of EV sales in 2018 and then rising to 73% in 2019. Then in March 2020 Tesla began delivering the Model Y which further increased the chasm over PHEVs, with BEV sales in 2020 climbing to 78.7%.

Also contributing to the decline in PHEV sales as a percentage of total EV sales was the discontinuation of two of the top-selling PHEVs, the Chevrolet Volt in 2019 and the Ford Fusion Energi in 2020.