If you have EU-spec D2 upgraded with red US lenses you might want to connect those additional additional 'side lights' from US lenses to your turn signals or to your fog lights.
Yes, in US style taillights there is one additional bulb which you can see on the right hand side of this picture. EU-spec cars dont have electrical wiring for that bulb, but it is easy to connect.
There are electrical contacts reserved under the black plastic cover. All you need is the following electrical parts to connect those contacts directly to the bulb:
1. Angled contact housing 211 971 921 -- 8 items
2. Repair wire 000 979 207 -- 4 items
Installation is 'plug and play'. No soldering required.