Should be the days when they just get it cleaned too. As for popularity I think there is somewhat of a bias in why people chose which colour. For example, the dark grey has been available in two different versions between 2011 Smoky Granite Mica and 2012 Nebula Grey Pearl version. Could mean Lexus didn't like the colour they had, or wasn't selling enough in 2011. Nebula Grey Pearl was also offered in a F-Sport Special Edition (only others were White and Silver). Obsidian black has been available for awhile on Lexus vehicles and many people enjoy it. Lexus is just now starting to use a new black called Starlight Black Mica on newer vehicles but still offers Obsidian for F-Sport versions.My Lexus sales guy said to me that people who buy black cars are happy on two days - the day they buy it and the day they sell it.