There are 2 reasons why I recommend the online medium to sell your used car.
No one does anything for free. Every intermediary that gets involved in the process of getting your car sold, takes a cut out of the value of your car. It is not uncommon for dealers to make 10-15% fee from the sale proceeds. The dealer may or may not tell you about the fee but he always takes the cut directly or indirectly.
The price that you finally get for your car, depends largely on the number of buyers that see your car. With more than 10 lakh buyers looking for used cars on the internet, you can rest assured that you shall get the best price for your car.
A video about how to sell used car yourself
Should you pay money to sell your used car
Some of the established websites ask you to make a payment to get your a premium listing. In my experience there is no need to do so as people planning to buy used cars are quite price conscious and they go through the top 10 websites looking for a bargain. Instead of paying some website to get a premium listing, focus on closing the deal with prospective buyers.
Try to provide confidence to the buyer of used car
Most people looking for used car are worried about getting stuck with a car that is not good enough. Hence the trick to getting a good price is to give them the confidence that you are an honest person and you are not hiding any detail from them.