The question as to how long it takes to sell a second hand Porsche car online is difficult to give a definite answer to. You could offer a second hand Porsche car for sale online in the morning, and end up striking a good deal before the end of that very same day! You could also offer a second hand Porsche car for sale online today, and end up going for a couple of years (or more), without ever getting a serious buyer for the vehicle. So nobody can tell you with confidence that it will this long (or that long) to sell a second hand Porsche car online.
Ultimately, how long it takes to sell a second hand Porsche car online depends on several things. It depends on the condition of the Porsche. It depends on the strategies you are using, in trying to sell the Porsche online. And it also depends on the price at which you are selling the Porsche.
All in all, it is critical for you to appreciate that selling a Porsche online is not like selling good over ear headphones under 100 dollars online. Neither is selling a Porsche online akin to selling headphones for IOS devices online. A Porsche costs much more money. As a result, the potential buyers will tend to take many more factors into consideration, before deciding whether or not to buy the second hand Porsche you happen to be offering for sale online.