Tesla Motors Inc. is introducing Model $3$ and planning to deliver $400,000$ cars at a retail price of $$30,000.$ And, $40\%$ of these sales would have resulted from the Model S regardless of the sale of Model $3.$ What is the incremental revenue from Tesla's introduction of the Model $3?$

$$4\mathrm{.}8$ billion

$$7\mathrm{.}2$ billion

$$6$ billion