need help finding the name of this vampire type movie

[DRILL]

Saw a movie when I was young, I'm guessing early 80's, late 70's, saw it at a drive inn with my parents.  a group of teenagers travels to a desert area, they stop at a gas station/convenience store and by something, outside they hear something, they go outside and the dog is dead.  later they travel to a mountain area, everyone disappears except the guy, who is dating one of the woman, eventually he finds them, they are all "vampires" involved in some ritual thing, he walks up to his girl, who is laid out on a table or whatever and looks at her, then her face sudden;y transforms from being young and beautiful to old and wicked, can't remember the rest.  Help!

[Rayo Casablanca]

Could be The Velvet Vampire
http://www.imdb.com/title/tt0067929/

It made the drive-in rounds long after it was made.

[d]

no thats not it, thanks anyway.. this is about a group of teenagers, I think one by one they get "converted"  she's the last.  when he walks up on her in the ending during their ceremony, he looks at her and she's laying there, looking normal, then her face changes and he realizes she's on of them now.

[Kester Pelagius]

Definitely not VELVET VAMPIRE, sounds vaguely similar to THE LOST BOYS, but that's not it either.  Can't find anything in the Vampire Book that matches.  Try a search on this site: http://www.vampyres-online.com/index2.html

[RCMerchant]

It may be LAST RITES (1980).

http://www.imdb.com/title/tt0081034/combined

[Dustin]

nope, definately not velvet vampire or last rites, could it be that my memory serves me up vampire but it was another type monster?  I believe it was a bat that killed the dog, i also believe it was during the day.