Halogen headlights are the standard headlights on most cars sold today. The headlights that are "bluish" are the HID or xenon headlights, which I think are standard equipment on the current generation X5.
Anti-freeze is usually diluted 50/50 with water -- I can't believe it could possibly catch fire.
This is an incredibly badly written story, the most incompetent police investigation short of a banana republic, or time to break out the tinfoil hats. (Arkancide, anyone???)
Remember, the top agency on this is BATF. Nuff said.