I own the cutlass in the movie milk money
Can anyone tell me how I can verify that.

You can post some pictures on the main site (click on the link "Back to the site") then search for Milk Money in the search bar. Once you've found the Cutlass, click on it, and at the bottom there's a link that says "You can store pictures on the site" click on that and upload the picture. From there you can copy the link and insert it into your message.