I was reading a post on No Impact Man, and looking at this graph in particular when I noticed the comment, "Reduce miles travelled per car annually from 10000 to 5000," (to reduce carbon emissions by one billion metric tonnes).

It struck me that there are a number of people who receive a car allowance, and to maximise their tax benefit it is preferable to drive a number of kilometres (what is it these days 30000km maximum unlogged?)

So, do our tax laws encourage driving? What would happen if people were penalised for driving more (fuel levies already do this)? What would happen if we could get tax refunds for driving less?