Parsnip wine needs a fairly long time to mature and then acquires a sherry-like taste. If you prefer a sweeter wine you can add sugar later. English granulated sugar is derived from sugar beet and therefore more compatible flavour wise with parsnip.However, blending parsnip wine with an undistinguished white wine from concentrate can improve it's character.
I recently made a very acceptable Sauternes type wine, using a combination of parsnip, grape juice and bananas.
I still have loads of parsnips in the ground, many if not most will come up small and misshapen, so I'll use these to make a Bordeaux blanc, in combination with grape and pineapple juice.
I have done a second 'pressing' of parsnips for a second brew which turned out as good as the first.