I'm a bit late to the party now but just for fun, I just pulled the light carrier out on my car and had a look. It's exactly as buddy describes. Five bulbs, three 1156, one yellow 1156, and the plug-in type is for the reverse lights.

It's quite interesting that they're doing everything with single-filaments. I wonder if there's any extra wear on the filaments because of the voltage variations?

 

What's really strange is that none of the European cross references I've been able to find even make reference to two filament bulbs...maybe this just isn't the way they do things? I assumed when I found the GE reference, and given that the red-lens bulbs were all dual-brightness, that they must be dual filament. But hey, learn something new every day, right?

 

Absolutely!

Someone ought to tell GE that the chart on their site is wrong...

 

What's even stranger is the bulbs in my wife's 2001 US X5's tail lights. There are two bulbs in the red parking light/brake light section. One has dual brightness levels and the other has only a single brightness level. Now here's the weird part: The one that has two brightness levels is a single filament bulb, yet the one that has a single brightness level is a DUAL filament bulb .........Obviously only one of the filaments in that bulb is being used (the dimmer one), so why put a dual filament bulb there? It can't even be that the brighter filament is used as a foglight in non-US markets because the X5 has a separate dedicated section for the rear foglights.