matching numbers?

Scarcity vs demand is what drives up price. Nowadays, it is difficult finding a car with the matching #'s engine or transmission. It's even more difficult finding a car with both. Matching #'s should command an asking price higher than that of the same car without matching #'s. There isn't a fixed percentage. It varies from model-to-model. you just have to research the market of the car you are trying to sell.