I don’t think so. AJAX is Asynchronous JavaScript and XHTML (or something like that) - the JavaScript on your page is what causes it to call the server-side routine to search the database. Basically you trap the “onblur” event from your selection (i.e. when the user tabs away having chosen “BMW”) to call the short server routine which then retrieves the data and displays it as required.
The JavaScript doesn’t need to be overly complicated - the actual connection code is widely available and after that it’s simply a case of hooking onto the appropriate event in your page (often losing focus from a control, or clicking a button), getting the data from the form, calling the server routine, and inserting the results into the document. I haven’t got a lot of JavaScript knowledge but have managed to get it working using some of the many tutorials kicking around the web.