You will be arrested and thrown in prison for life.
Of course if you have an accident, and really demolish the car, you may get off easily, because you destroyed the evidence. What you should do is buy the car, and as soon as you get it onto a public street, completely demolish it in a severe accident. Maybe drive it into a concrete bridge pillar doing 150 mph. This way, no one will ever know if there were plates or not, because the car will be so badly demolished.