These are not the words you want to hear from your mechanic after a routine tune up. But there I was, learning that my car needed a new head gasket, and maybe a new fuel injector as well. My 2011 Ford Escape just went from a reliable family car to a certified clunker.
After doing the math, it seemed pretty clear that my best bet wasn't to repair the car, but to sell it. Unfortunately, a car with major engine trouble isn't the easiest thing to sell. In fact, when I looked up quotes on sites like Carvana, it looked like I could expect to get $500-600 for it, essentially selling it for scrap.
But after some thinking, I decided it wouldn't hurt to put it up for sale. My hope was that someone would buy the car with the intention of fixing the engine themselves, either getting a deal on a fixer-upper, or even making a quick buck by flipping the repaired car. The worst that could happen was that nobody bought it.
But selling a car with engine troubles is a bit of a challenge, and it takes a well-crafted ad. With a little work, I'm sure I could write an ad that does the job, but this car was causing me enough trouble already, so I decided to see what AI could do.
For this experiment, I turned to ChatGPT. Though I'm sure that there may be custom GPT tools for writing classified ads or selling cars, I usually stick to the basic features of a free account.
And since all I really wanted was a written ad I could use on Craigslist and Facebook Marketplace, regular ChatGPT was more than adequate for the task.
What's great about this is that you could do the same thing without even signing up for an account. OpenAI's GPT-4o model is free to use for a limited number of prompts, but even the less capable GPT-3.5 is up to this task. And if you prefer another AI assistant, like Google Gemini or Microsoft Copilot, pretty much every one of them is capable of doing the same.
If you really don't want to use OpenAI's site or app, or sign up for anything else, you can access the same tool privately through DuckDuckGo's anonymized AI chat, which gives you free access to ChatGPT-4o, along with Claude 3 Haiku, and open source models like Llama 3.1 70B and Mixtral 8x7B.
The Walkthrough: From Specs to Finished Ad
A good rule of thumb for getting good results from ChatGPT is to bring your own information. In this case, that was basic information about my car. Though I had a list of specs covering details like engine size, interior type, and the like, that was information I could copy and paste without needing to format it. What I wanted was a written ad I could copy and paste for use on local classifieds, or Craigslist and Facebook Marketplace.
It's not the most carefully worded prompt, but it has the two key elements: A clear request (write a Craigslist ad) and the relevant details. Could I have spent time specifying things like format and tone? Sure, but simple prompts have the benefit of being quicker to write.
The response is pretty great right from the start. Despite my minimalist prompt, it gave me more or less what I wanted, and it included the information I provided about the model, mileage, and repair needs. The formatting is a bit too much, and the tone feels a little stilted, but we're already 80% of the way there after just one prompt. All that's left is to dial things in a bit more.
Here I refer back to my first prompt, since it already has the details I needed. This is also when I address tone -- which is easier to do as a correction after the fact than it is to proactively discuss in my first prompt.
These minor fixes resulted in an improved version of the ad, which directly speaks about the overall maintenance history of the car and even expands a bit on the section about who the car is perfect for.
Leaving the ad copy aside for a moment, I let the AI do a bit of thinking for me, asking about pricing. I didn't need it to do the simple math -- and you can see from the highlight why you shouldn't -- but using it as a sounding board was useful as I figured out how I wanted to price my car. The ability to digress on a related topic and then come back to the matter at hand is another great way to use the chat interface. But by keeping it all within the same conversation, it adds further information and context for the AI to use, which is also handy.
But this is also a great example of where many AI tools fall flat on their face. The highlighted line there talks about the price of repairs and price of parts, but applies exactly the wrong logic to it. The parts were a small portion of the overall repair costs I'd been quoted, but ChatGPT assumed the numbers were supposed to be added. It's a good thing I can do my own math!
Why does this happen? Because it's not a math model, it's a language model. The basic version I used in this example isn't built to handle math and numbers, and it's not always great at logic since it sometimes gets things exactly backward. Even when the math adds up, the logic may be skewed. You always, always need to review what the AI produces and watch out for these sorts of mistakes.
Ultimately, I did lower the price and even added "or best offer" since I was trying to sell a vehicle that needed repairs.
Here I reiterated that I wanted it in a format that would work for Craigslist and Facebook, but it wasn't until after the fact that I realized I wanted something specific.
The back-and-forth format of the chat interface makes exploring these sorts of half-understood requests a lot easier since it only takes another prompt to try something else.
ChatGPT added the new pricing information and updated the ad with some relevant notes -- and it even got the logic right this time! Interestingly enough, you can see that the wording changes a bit with each pass, instead of only editing the relevant section of the text. The revisions still work, but in many cases, you'll see something you want to use in an early draft that disappears as you try to refine other elements. It's a good idea to look over each iteration, since most AI tools will generate fresh copy with every adjustment.
And while I like the overall text, there's still the issue of formatting. I'd better clean that up.
And there's the reformatted version of the text, which more or less includes all the key elements I asked for over the course of the conversation.
In just five steps I had a complete ad, ready to go. It not only addressed the general need (selling a car) it was also tailored to my specific circumstances, included reasonable pricing, and had the relevant details, all in a format that was ready to copy and paste. Pretty good for less than 10 minutes of work!
But the real question is whether that ad would actually help me sell my car.
Off to Craigslist and Facebook I went, using that ad and the detailed spec list I already had. Throw in a few photos of my car, and viola, the selling had begun.
I wish I could say that my marvelous ad magically made me immune from the dozens of scammers that circle around classified ads like vultures, but it didn't. I still had to wade through VIN lookup scams, half-hearted buyers, low-ballers, and looky-loos, but by the end of the week I had a few potential buyers lined up to look at the car. Of those, two actually showed up to see the car, and one made me an offer.
After some negotiation and haggling, they had the car and I had $2,300. Not quite the $3,000 I had hoped for, but a fair bit more than the $600 I initially thought I'd get.
What Can ChatGPT Sell For You?
Writing simple ad copy like this is the sort of task that LLMs were made for. By providing just a little bit of factual information and being specific in your request, you can go from zero to ready-to-post faster than most people can look up what a good used car ad even looks like.
But what works for selling a car will work for selling almost anything. This technique could also be applied to things like Ebay listings, real estate ads, job postings, and more. Some folks are even using similar techniques to write their dating profiles on sites like Tinder.
As experiments go, this one was pretty successful. It not only sold my car, it put some extra cash in my pocket, too! But I think my favorite part was how easy it made the parts of the process that are usually boring, and made it super simple to tailor everything to my needs. If you're looking to streamline your own boring tasks, this process should help you get the job done.
