Depends on the depth of the spacers, but 20mm non-hubcentric will be too long for a VW. 10mm non-hubcentric spacers at the rear is ok, as there is enough of the lip sticking out to centre the wheel, but up front it'll need to be more like 5mm or so!
Any thicker than this and you need hub-centric spacers. Also note that hubcentric spacers smaller than 12-15mm or so wont fit over the hubs properly, as I found out to my annoyance the other day!
