The Gendarme and the Creatures from Outer Space 1979 Le Gendarme et les Extra-terrestres

The bungling inspector Cruchot finds himself trying to save the residents of St. Tropez from some oil-drinking humanoid aliens. The only way to tell the aliens from the real people, besides their constant thirst for oil-products, is that they sound like empty garbage cans when you touch them. Chaos is ahead.