Over 6m electric vehicles needed in UK by 2030

Over 6m electric vehicles needed in UK by 2030 | Electric Vehicle News: "More than six million electric vehicles will be needed on the UK's roads by 2030 if CO2 reduction targets are to be met, according to WWF."

But isn't this the wrong way around? The only thing needed is to reduce the number of fossil fuel vehicle; I think oil price and availability will do wonders for CO₂ emission reduction. Although in the longer run it's of course coal which is the major contributor.