I was looking for a major brand alternative to the invisible turn indicator lamps (front and rear). I came across the Osram Diadem lamps.

"When they are not indicating, Diadem signal lamps have an opal appearance that looks very similar to the silver backing of modern headlights. The classic look of amber indicators is consigned to history. Only when they are flashing do Diadem lamps produce the characteristic amber signal light of the usual intensity."

It is also rated at twice the life of standard lamps.


Osram Diadem

I located a source in the US:
http://store.candlepower.com/diadem.html

They also carry the full catalog of Narva lamps, which are made in Germany.

I have yet to locate a major manufacturer that carries the "invisible" side indicator lamps. The stock lamps on my E90 has an amber bulb with a silver cap.

 

Try look for "Pilot" brand from amazon.com ... like XC-194A for the side & XC-3057A for front/rear blinker.

 

The Osram Diadem bulbs arrived. They have a light reflective coating with just a hint of amber. The amber is still visible in our light housing, but less than the stock amber. I'm now awaiting the BMW silver bulbs. They look like they still have a hint of amber too.


I'm avoiding specialty brands for now. They are either too dark, too hot, or have short lives.

 

I bought some BMW side repeater bulbs from the dealer and they are amber bulbs with the ends dipped silver, the amber is visible if you look at an angle but face on you only see silver.