Complex sentence: When their car breaks down in the desert, the four find a seemingly abandoned house along a side road and in the barn they find a silver 1971 Chevrolet Chevelle with gasoline fully filled.
Split into simpler sentences: When their car breaks down in the desert, the four find a seemingly abandoned house along a side road. In the barn, they find a silver 1971 Chevrolet Chevelle in working order with the gas tank fully filled.