A few days after got my Z4 I noticed only one fog lamp was working. My car has xenon headlamps so the solitary fog lamp looked very yellow in comparison. I was concerned that if I bought one fog bulb it would be a different colour to both the existing working bulb and the headlights so I decided to buy a pair of H11 bulbs. Prices vary hugely but I eventually went for a pair of the 'xenonesque' bulbs that claim to be brighter and whiter than normal halogens. Got mine from Xenons_uk ebay store £6.94 delivered for the pair. I went for 'super white' rather than ice blue as I didn't want any Chav Saxo/Corsa theme going on and I stuck with 55w rather than upgrade to 100w bulbs. For under 7 quid I was not expecting to be overwhelmed but I can't fault them for the price. They are definitely a lot whiter than the originals with no blue tinge and are a close enough match to the headlights. I immediately ordered a pair of the 501 sidelights from the same people in 'ultra white' to whiten those up a bit too (£1.95 delivered for the pair). These were again whiter than the originals but not as white as the fog bulbs - maybe should have gone LED with these ones but never mind still an improvement and the sidelights with just the fogs look pretty good as DRLs now.