It used to be an easy choice for green drivers. Toyota Prius ruled the road with top fuel economy and reasonable pricing.

But the competition is getting serious with more plug-ins like the Prius Prime I tested this week, more all-electrics and more traditional hybrids. For example, Chrysler’s Pacifica minivan now is available as a plug-in hybrid. Plug-in and all-electric models soon will join Honda’s original line of Clarity fuel-cell sedans.

Prius Prime, formerly Prius PHV (plug-in hybrid),…