Spyder manufactures replacement headlight assemblies for the Z4 e85. There are a few dealers selling them on Amazon and E-bay. I ordered a pair to replace my headlights assemblies that have the wire insulation deteriorating and falling off causing shorts. They were stated to be for Xenon models. They were, but made to convert the Xenon to Halogen per the installation documents and Spyder Tech support. Per the installation instructions they are plug and play into the original wiring harness. I returned them for a full refund due to false or misleading advertising and not what I was looking for, to keep the Xenon bulbs. I replaced the wiring in the original headlight assemblies and plan on buying Hella assemblies in the near future.
Why replace Xenon with Halogen? Xenon provide brighter light.