I had great results by using the $10 kit from Harbor Freight, simple sandpaper pad that attaches to a drill, some elbow grease and then the polishing compound and my headlights looked new for over a year (until a carsh meant new headlights were in order anyway)

__________________

2008 550 - Carbon Black/Black - M-sport, Cold Weather, Premium, NAV, Comfort Access, Logic 7 (LOADED, every option except night vision) - mods done: RPI GT exhaust, RPI scoop, K&N filter, 20" wheels. planned: ESS tune, CKS coilovers, CF Hamann style lip, RD Sport trunk spoiler, ESS SC kit, Magnaflow headers

Previous 3 cars (the 550 is my 38th car):
2005 530i - Prem, Sport, NAV
2006 Jeep SRT-8
2003 Infiniti G35 coupe