META tags are just one method of getting a search engine's attention. Alta Vista search results rely heavily on META tag content.
However some engines, like Excite, ignore META tags all together and search through the the text on the first couple of paragraphs on the home page. As for YAHOO, it doesn't search anything, it's a static database file!
The best way use the search engines is to create what are called "gateway pages" for each one. In short, you create a separate home page for each search engine (I'd suggest doing this for just the top twelve or so), that is optimized specifically for that search engine. For example, a page designed to show up in an Alta Vista search should contain detailed and extensive keywords in the META tags, and Excite gateway page should include those keywords in the first two paragraphs of text, etc etc. This will help you get better placement in search engines, thus, more hits.
Lastly, the number one method of generating leads and hits is to advertise your URL prominently in all your print, radio and tv ads. This is a proven method for driving hits, leads and sales to your web site. It's amazing how many dealerships don't do this one little thing