"Drive-In Massacre" http://www.beardyfreak.com/rvdriveinmassacre.php
Despite having a gore-tastic and satisfying opening murder the rest is almost unwatchable, atmosphere free (it's more accurate to call it
"Car Park Massacre") , badly made, tedium.
This is a truly foul pile of putrid matter masquerading as a horror film that serves less purpose on God’s green Earth than a eye burrowing parasite in an African watering hole.
It may have been one of the first true examples of the Slasher sub-genre, that would get honed to perfection a few years later…but being the first crap example of something that would get much better is hardly a triumph to shout about.
Avoid.