As I understand it, the only difference between the 500E and 300E Euro lights was the glass lens and the shape of the aux reflector - most specifically, where the bulb was located in the reflector. The 500E lights have a clear glass cover over the auxiliary light, and the bulb is dead center in the reflector, making it a long range pencil beam driving light. The 300/400E lenses have thin verticle scribing over the aux light, and the bulb is off center, making it a downward and wide spreading fog light. Both the fog and the driving are supposed to use the same 55 watt H3 bulb.
The yellow goes away with the US lights, where the yellow effect comes from a tint shield in the reflector. My old H3 bulbs from the US lights were yellow in that car, but white when moved to the 300E Euros. I changed them for some coated bulbs that are pale yellow on the ground, slightly irradescent yellow white when viewed from the front. Too many cars saw 4 lights and assumed I had my high beams on when the bulbs were white, so I changed to the yellow ones - problem solved.
I could never find 500E Euros, just replacement 500E lenses. I decided a pencil beam didn't make that much sense in SoCal, so I went with the 300E lights. Hope this helps.
[Edited by JCE on 02-04-2001 at 02:13 AM]
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E