use custom fileds(tags) as subject in contact form 7

hi all,

I created a form that allows people to publish their car on my site.
I created fields that enable users to specify the vehicle manufacturer, the vehicle model, and the year it was built.

what i need is that the three fields I mentioned earlier will be displayed as the subject of the email message I get after the user clicks the submit button.

I am attaching a link to the image of the form and the fields that I would like to include on the subject are marked.

Thanks in advance