you could create a form where the users input their email and name and message to be mailed and all the variables such as $reg and $model, then when they submit the form, call the mail() function to pass all those variables into your message or subject line, such as:
mail("lee@mhautobody.co.uk","$reg $model","$message","From: <$user_submitted_email>");
mail("to","subject","message","headers")
this is a rough script that hasn't been tested, but is similar to what i use. it also saves the user time from opening their mail client; they can just send the message right from your web page.
hope this helps
~JOSH
