On my '99 A3, I could have purchased ABS as a 'dealer installed option' for around $900. (I could look on my notes if anyone wants the exact figure. When I say I have all records for my car, it includes notes from the weekly calls to the dealer to see if she could find me the Windsor Blue/Orlando package/dark interior/sunroof combo I wanted!

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While ABS was on my list, I did not go for the ABS option. I don't know about the disk brakes, but mine doesn't have them and it was on the last ship of A3 TDIs to hit the Northeast port. Side airbags definitely were not an option.
When I got my car, New Beetles were showing up in showrooms, and they had side airbags. I am sure I asked, and I am sure my saleswoman rolled her eyes. Just like she did when I told her I wanted the full-size spare, and intermittent wipers.