This can be found by studying the car and learning all of the ins and outs of your particular car. If you're planning to sell the car to a collector to pull the most money out of the sale beware that most collectors are shrewd and they know every nut and bolt on the car, they are only buying as an investment.
The things that you will need to are the numbers of the car. First, the code is very important to know this will tell you a big part of the story. It will verify the year of the car the day the car was built and the number of the car as it rolled off of the line on a GM car.
Beyond this, you will need to learn the options that were available in the car, and what ones your car has. You will need to know if they are standard options that your car came with or if they are rare and hard to find options.
Obviously, the rarer the options the more collectible the car is. You will need to learn what engines were available in your car, what transmissions were available in your car, and what rear ends were available for purchase in your car.
All of these things can give you bargaining power. Learn about the interior options also. Such as the material that seats are made out of, did the car have a center console or was it available? You don't want to try to add options that your car didn't have from the factory, this will never work.
If your plan to have another person or company your car then you need to understand that they will need to make money too. There are two ways for them to make money, one is to collect an upfront fee to sell the car, this is something that I don't usually do.
The other is the way that I do it, that is to look up the fair market value of the car and sell the car for that amount or as close as I can and then take my cut off of the top, this is how I prefer to do it. Bother ways are legitimate and they both work fine, for the per son selling the car it works out the same.
The other way to sell the cat is to sell it directly to the re-seller. This is called flipping a car. What you have got to realize about that is that you will not sell him or her the car for fair market value, that is what they will re-sell the car for, and they will haggle the price down until they see a profit on the sale.
Most of them are not scammers and they will not try to rip you off. They are just looking to sell the car for a profit. This means that they have to get it for less them fair market value, and they usually have a number in their mind that the car is worth to them.
I forgot about a broker, you can sell a car through a broker also. They a fee to sell the car and this is where their money comes from. Brokers usually have a lot of sales contacts or people looking to buy certain cars, this can also be called a locating service. They will usually collect a fee on both ends.
A locating service will charge a fee to the buyer to locate the car, and then to the seller to sell the car. This is where their income comes from. They usually can find the customers that are willing to pay a good price for the car and line them up with the perfect seller. They do this by knowing a lot of people.
I hope this will help one or two of you in the buying or selling of your cars.