It is now common knowledge to have an SEO strategy for your dealership in your city. That is your home turf, you got to defend it. This article talks about why is it important to defend your post in your city, and also, go on the offensive on competitor strong holds.

Google is undoubtedly the leader in the search industry. The next in rank is Bing. However when it comes to customer confidence, Google has the market cornered. Google weeds out the junk/spam sites with its proprietary algorithms that it keeps updating on a regular basis. Google recently updated its algorithm with the Panda update (http://en.wikipedia.org/wiki/Google_Panda)

Most users today, search for dealerships in their zipcode, and slowly go further for more options. If you are just miles away from your competitor, it makes sense for the buyer to drop by your location, or atleast check your inventory online. It's for this reason that creating SEO not just for your city but also for cities where your top competitors do business:
Let's say you have a competitor in Pembroke Pines, about 20 miles from your dealership in Pompano Beach. The city is medium sized but the dealer group in Pembroke Pines already has the market cornered and they have the only Chevrolet of Pembroke Pines. Just about everyone in town knows about Pompano Chevy.

When people want to buy a vehicle or have their Chevy serviced, chances are they're going to search Google for "Pembroke Pines Chevrolet" or "Chevrolet of Pembroke Pines". Those people aren't your targets. It's the people who do the search for " Chevy" or "Chevrolet Dealers" or "Chevrolet Dealers in Pembroke Pines" that you want.
Why? Because since they know all about the dealership and may have even done business with them in the past, when they go to Google to search for "Pembroke Pines Chevrolet", they're looking for an alternative. They're looking for you or whatever dealer is ranked near the top for that search.

People trust Google's opinion and we ask it all the time without noticing. If you're in the top 5 (preferably #2, of course) for the terms " Pembroke Pines Chevrolet" and "Pembroke Pines Chevrolet dealers" you have an opportunity to sell more cars as well as keep a deal from going to your competitor.

Defend your own backyard as much as possible. Once you're set in your own city, start going after your competitors. It's this type of strategy that will separate you from the other dealers in the area and can have a dramatic affect on your numbers as well as their numbers.