Price vs. Convenience is the main trade-off you face in deciding how to sell your car.

Private Sale
You will usually be able to get the best price for your vehicle by investing the time, effort, and money necessary to sell it "retail" to a private buyer/consumer -- someone who doesn't plan to immediately resell it. You will have to develop an effective classified ad, place it, make yourself available to handle phone inquiries, appointments (and no-shows), show and demonstrate the vehicle to serious and not so serious shoppers, negotiate over offers, and worry that the check will clear. In addition, it is a comment on our times that in considering how to sell a vehicle, concerns about security are increasingly not far behind considerations of price vs convenience for men and women of all ages. Retailing your vehicle usually means meeting strangers at your home (often in the evening when it may be dark) to show the car and accompanying (him? them?) on a test drive. Many sellers with concerns about security have adopted strategies like showing the vehicle only on weekends during the day and having a friend or relative present when they do show it. Still others feel that concerns about security tip the scale toward selling the vehicle "wholesale."
Trade it in with dealer

Selling a vehicle "wholesale" is selling it to a car dealer as a trade-in or to an auto wholesaler -- in either case, to someone who plans to immediately resell it. The dealer or wholesaler will need to purchase your vehicle for substantially less than you could probably get if you sold it yourself. Otherwise the dealer will not make enough profit when the vehicle is resold. And if the dealer or wholesaler doesn't think he/she will realize enough profit margin when reselling your vehicle, he/she won't buy it from you at all.

Tax implications

Trading your vehicle in with the dealer offers considerable tax savings for buyers in provinces with 15% HST. The trade value is deducted from the price of the new vehicle and you pay tax only on the difference.
Example Price of new car is $20,000.00 less trade in of $5,000.00 = $15,000.00 plus tax of $2,250.00 = $17,250.00
Price of new car without trade is $20,000.00 plus tax of $3,000.00 = $23,000.00
Tax advantage $3,000.00 less $2,250.00 = $750.00
This means you would have to sell your vehicle privately for more than $5,750.00 to gain any benefit.

Tax Warning ( PEI residents buying out of province )

As a PEI resident buying out of province you will be required to pay the GST 7% to the selling dealer on the difference, however when you get back to PEI and go to register your new vehicle you will be required to pay PEI Provincial Tax on the full price (pre-trade) of the new vehicle.