Looking at your AutoTrader Listing on the 2019 Mercedes-Benz CLA 250 here are my suggestions.
Photos- The photo quality is good, but you aren't showing the options the vehicle has. Build the Value. Our photos should sell the car. It looks like it should have a panoramic sunroof, but there isn't a photo of it. Your description shows that it has applecar play.. turn the vehicle on and take a photo of it. You should have pictures of the radio screen on and working. Show the different screens/pages and show the backup camera.
The fair market range according to the widget on that page is $22,455 - $25,088. So with your vehicle being priced lower than that, it should have the "Great Price" Badge but it doesn't. That means it probably has a branded title for either a manufacturer buyback, structural damage, or total loss.
That means you need to show why it's still a good buy. Maybe add a short video of it running and driving.
Hope this helps!