Where is the best place to market my Porsche?
If you are in the USA, take it to a CarMax dealer and see what they will give you for it. What year and model is it and how many miles?
I am guessing it is the car posted on your garage here on the site. If so disregard my post as this car is too old for CarMax.
The key to selling fast is to clean it up and detail it really nice and then price it to sell. Try Craig's list or cars.com, Autotrader, or trade it in at a dealer but you will get bottom dollar that way.