Don't get me wrong, increasing road tax is annoying, but it hardly contributes to the cost of motoring.
I do agree with reasoning behind the increase - its there to encourage you into buying a more econoimical car and realisticaly the road tax hardly contributes to the cost of the motoring.....
10,000 miles per year - 30mpg - 110p per litre works out at about £1700 and if you then add £600 to £700 of insurance and the cost of financing your car coumpounded by its depriciating value, the £170 tax doesn't look too bad
Still - I'm signing up if it saves me a few quid!