well i'd go for the 5000k. most cars with HID's out there are 4300k so 5000k will look "bluer" than the rest and the amount on non HIDs are a fraction of cars with halogens. its mostly perspective regarding the "blueness" of the color temp.
5000k will have considerably more lumen output than 6500k. brightness > color temp.
5000k blowbeam + fog
