I think most people expected a fall in revenue once they scrapped the tax disc, I've never understood the logic of doing that?
My cars are always taxed yet twice now I have received letters saying the car is not taxed, they sort it out when you phone them up, so they are trying to do something, unfortunately targeting the wrong people!
Also, the car tax system is unfair in a few ways, when a car changes ownership the seller has taxed the car until the end of the month, yet the buyer has to tax it from the start of the same month! So the government gets twice the amount of tax for that month! Seems they are using the law abiding car owners to compensate for those who do not pay!
I also find the high tax rates for large cars to be very unfair, this affects cars newer than March 2006, tax of over £500 per year is unfair to me, remember that we are heavily taxed on fuel so the more you use a car the more you are taxed, an automatic system, so no idea why they need such high ved.