I would like to know the significant changes that Acura added to the El as it evolved from 2001 to 2005. Eg. when did they change to rear headrests and other such minor or major additions. I know they changed the front to fog lights but I don't know what year. I'm considering buying one of these used and I would like to know which year is best. Also I am only looking at premium models with leather and sunroof.