High taxation in general, plus high car taxation, means that taxes will be allocated towards alternative transportation options. In Denmark this has meant bicycle infrastructure and culture which has been shown to make humans both happier and healthier. Not to mention that older cars means a lighter touch on the earth (heavy metals, fuel, etc).
Taxation is a good way to apply pressure, and I think we often overlook the power that high taxation has for good policy. Instead we get lower taxation and 'let the market decide' which often results in a more wealth inequality and worse pollution among other things.