Hi Bill unfortunately this is not currently possible because to my knowledge the only email client that currently supports video is Apple mail. So for now your only option is to have an enticing screenshot of the video with a big red play button that when clicked links to a landing page on your site and auto-plays the video. Although this may not be as seamless as embedding a video directly in an email it does provide the added benefit of having the customer on your website where they may decide to start looking around at cars. The ability to incorporate calls to action, buttons, lead forms, etc is another additional benefit of using a landing page for videos.
In addition to the screenshot of the video make sure to include an enticing text hyperlink below the image because as Neil mentioned, many email clients don't automatically download images, so the text link is a good backup. The one thing you have to be a little cautious about is hyperlinks and images in an email can cause your emails to get caught by users' spam filter more often than a plain text email would. Sometimes a simple conversational email is the best way to go, all depends on who you're sending it to and what you're looking to accomplish.
Update: Researched it real quick and it looks like the Outlook.com web client also supports HTML 5 embedded videos. You can use a fallback image / screenshot that MOST other email clients will use instead if they don't support videos. Another creative option would be to create a short animated gif version of the video and link it to the full version.
