Sounds like you have the early 2.0tdci (130) auto there... That particular set up was only available for about a year after the launch of the mk4 and was 2 tax bands higher than the more powerful manual equivalent. Since then they have increased the power up to match that of the manual, and in doing so reduced the emissions so both manual and auto variants are in the same tax band, (Although the auto does still emit more CO2, as is almost always the case when you attatch an auto gearbox to an engine.) I know this is no help to you now but we're also only a few of months away from a 160hp version of the 2.0TDCI for both transmissions.