MOLTEN ROCK, or magma, and gasses spew from the mouth of a volcano in the Hawaiian islands. As rock inside the earth melts, its mass remains the same while its volume increases--producing a melt that is less dense than the surrounding rock. This lighter magma then rises toward the surface by virtue of its buoyancy.
Although each automobile dealer has the option to release new models at a time it chooses, most companies release new models between September and December every year. In addition, some brands are showcased earlier in summer car shows.
Imho, a demo is a car sitting in the car yard. A new car is one that has to be delivered. My wife brought a Demo in April, it was advertised as a demo in the newspaper. We test drove it and knocked a few grand off the asking price, it had 21km on the clock when we left the dealership after she had brought it.