Sorry, I don't know either, I have a set of stock alloys in my basement that I pulled off when I went to steel but I don't have any scales. I like the steel and wheel covers as apose to a cheap alloy that will scratch if you look at it wrong. I relly don't think that the vw alloys are much lighter than their steelies. I do know it you go to a wheel like the Centerline forged aluminum they will weigh around 20lbs
one more tid-bit. I am sure you have seen this debate alot at the tdi club. If you go to a larger wheel, the general consensis is that it wil HURT you mpg. Even if the wheel is lighter. you will be adding weight further from the rotating center of your hub. even with the same outside wheel tire hight. The wheel weights more that the rubber you are replacing. You did not say you were going bigger but if you were going that way just wanted to let you know.
If you're looking for a really light rim, then check out Rota wheels. I had a set on my Integra in 15x7 and it was I think 13 lbs for the one I had. For comparison, the alloys I pulled off were 19lbs/piece.
You also need to keep in mind the road conditions. If you're in an area with lots of potholes and railroad tracks, you may bang up te ultralight rims enough to break the seal on your tires. Not a good way to improve milage by having to constantly stop and put air in the tires.