Remember when plug-in hybrid cars were the go-to technology for the climate-conscious driver? Turns out, they're not good for the environment, according to some experts, and they could be phased out by carmakers in the face of tougher European rules.

EU policy plans for plug-in hybrid vehicles (PHEVs), which contain an electric battery and a combustion engine, could mean the "transition" technology has a shorter lifespan than envisaged by some leading automakers.

Draft green finance regulations would ban manufacturers from labeling them as "sustainable investments" beyond 2025, potentially deterring investors. Meanwhile, planned rules on emissions of pollutants like nitrogen oxides could increase the cost of producing these cars.