I think its somewhat amusing that people think they need to do all this for craigslist.
First and foremost, its important that you understand that there are 2 kinds of people with regards to your car: 1) people that are interested in it, know what it is, and are willing to pay something close to what you are asking (which is maybe a bit more than the autos I've seen are selling for, but pretty close anyway), and 2) tire kickers, people that want to waste your time and jew you down, people who have a friend that might be interested, people that definitely for sure want it but need to make payments/get financing/go rob an old lady/want to trade a gun and a 4 wheeler, etc.
To further this point, let me point that that if I was in the market for a WS6 I'd be checking craigslist daily or at least a few times a week, and I'd be typing "ws6" into the search box, obvious. But if I really wanted one, I'd probably also type in things like "firebird," "transam," and "camaro," so that even if you had done a TERRIBLE job listing it, I'd still find it. And if I really wanted a WS6 and was in the mood to pay $6k for it, I'd call someone who had an ad without photos, and I'd go look at it.
If I was anyone in group number 2, I wouldn't do those things. I'd just look on craigslist, see it, think 'gee nice car,' and hit the reply button with stupid questions, whether you already typed the answers in your original ad or not.
So the point is that you don't need to "pitch" a car like that to people. At $6k youre above what a member of the general public will pay for that car on a whim. Youre selling to people that know what they want and what its worth and have the ability to pay for it. Just give them a few pictures of the car showing the exterior (2 3/4 shots, one from drivers front, one from passenger rear, cover the whole car), 1 of interior, and 1 of engine bay. This shows what you have to offer without being annoying, hard to browse on one's phone, and/or overwhelming. Guess what? Also less work for you! Give them a quick run down of the car. Miles, overall condition including anything obviously broken, but can also include anything significant that received recent replacement, location and your contact information. May also want to add if price is OBO or is Firm as this is relatively important to many buyers, and title status (if its free and clear, R title, or lien encumbered and you don't have titled on hand). If someone is interested and they need more info they will call! No one that is ready to buy that car is gonna say "Oh he didn't say if the windows were tinted and if the alternator was replacing in the past year so I'm out."
Now, having said that, if you just put that you have a 01 trans am for sale, you may lose out on people that just googled ws6, and you may lose out on people that are just frustrated from searching so much and are tired of emailing everyone with a crappy ad for a firebird because they are looking for a ws6. So make a good ad, but be aware that a good ad is quick and easy for you to make and gives a REALISTIC buyer the information they need to move forward.
And no matter what you put at the bottom of your ad, you will still get spam if you put it in craigslist (nearly guaranteed), and you will still get a lot of people that ask if its still for sale. Honestly, I deal on craigslist a lot and so many people put "don't ask me if its still for sale" and then forget to take down the ad, so I email or call them asking if I can come by and look at it tonight then learn its been sold for a period of time, that I often do incorporate the question of whether or not the item is still available for purchase into my initial contact.
Its a small price to pay for the ability to post free classified ads, viewable to thousands of local people for free.