Obviously a collectible item inside its original box is worth more than the item without the box, or even in a box that has been opened. But having said that, the real answer is that it would depend on what Hot Wheels car is inside the box. The value of Hot Wheels cars depends on their rarity and their condition. Obviously the condition of the car inside the box will be "excellent", but without knowing which Hot Wheels car is in the box, this question can't be answered. In addition, even if you had mentioned the car style inside, it still would be difficult to put a value on it since values are constantly changing. The best bet would be to go to Ebay and search for completed auctions with your box and car. You will find out what dealers are selling them for and what buyers are willing to spend. And lastly, the condition of the box is important. The age of the Hot Wheels is most important. If they're original cars from the 1960's and early 1970's an unopened box would bring thousands of dollars. Boxes were stamped with names of the cars inside and that would effect value, too. If it's from the 1990's or later you might be hard pressed to get retail value of approximately $1 per car.