Google announced a few months ago that they were going to start penalizing websites that were deemed to be over-optimized for SEO as an attempt to "level the playing field".  While many auto dealer websites shouldn't have an issue with this (your site provider should not only be up to date on Google's latest algorithm changes, but make sure your site is performing as well as possible), here are some things to avoid so you don’t over-optimize your website:

Keyword Stuffing: Google wants the content on your dealership to be relevant, quality, and valuable to users. This means that every other word can't be one that you are trying to optimize for.  Use your keywords when they make sense, but don't write choppy, difficult to read sentences just because you are trying to get more keywords on the page.

Non-Relevant Anchor Text: This is the highlighted text that website visitors click to visit another page. The anchor text should describe what is on the page that you are linking to, for example, "used Nissan Altimas" should send traffic to a page about used Nissan Altimas.  Having the same anchor text for all links, or anchor text that doesn't accurately reflect the content of the landing page for a link is spammy and is exactly what Google is trying to penalize with this update.

Having Hidden Text: Frequently, organic search spammers create extremely keyword-heavy text that is hidden or obscured from website visitors, but visible to search engine spiders.  Again, Google wants to reward websites that give relevant information to visitors, so there isn't much value (and potentially harm) in hiding content from visitors.  Text that is “white on white” or hidden under a “see more” layer may be penalized by Google, and could even get a site dropped from Google’s index.

As always, create your auto dealer website with your customers in mind, and the chances you'll be penalized by Google are highly reduced.  Talk with your dealership website provider to see what SEO techniques they are using on your dealership site and how they're making sure you're on good terms with Google.