The data base I use does not list a 2.0 td gsi
there are
2.0td Kw 1719Kg
2.4GSi kw 1730Kg
As I said before it not an exact science, and the lack of an exact match on databases means you cannot easily get at the manufacturers figure. Solution is to strip teh car down to its MIRO condition and take it to a weighbridge and get it weighed.
But from a practical point of view, unless you only have a Cat B licence, where the trailers MTPLM MUST NOT exceed the cars Miro, the small variances you have seen in our figures are a major problem. a few Kg or pecent here or there (except where there arelegal limits) are not going to make much difference.
Good towing is most affeceted by the driving style, farmore than weight ratios