NADA says that nearly 90% of the people that call your dealership buy a different vehicle than the one they called on*.
Think about that.
Your shopper is looking for an affordable SUV with a 3rd row, that's decent on gas. If you break all your web inventory into rooftops, you've blown the magic & power of a "unified front" that speaks to your customers needs.
Its simple (its the Pay Plan that makes it difficult).
You have a shopper that's "just looking". Do you hand the shopper a brochure to one store, or, a catalog for all your inventory. Which one gets read more? Which one gets saved for shopping references?
The proof cannot be debated.
Look at the site traffic stats of a single roof store with 300 units vs a multi-roof complex with 2000 units that has a single website presentation. All the metrics explode: Time on site, # of pages seen, visitor loyalty, visitor regency, they all go up. They end up so high that you'll rival stats that cars.com and autotrader.com enjoy.
Shopping time is NOT unlimited.
The more your stores absorb the shoppers time, the less time your shopper has to spend on other sites. This added time allows you to really hammer home the "value added" goodies that your mega complex offers.
Geographical problems?
CarSense & CarMax: Install a "sniffer" to geo-locate the shopper and "suggest" a store closest to you.
Used Cars Pennsylvania, Philadelphia, New Jersey - CARSENSE - Used BMW, Honda, Nissan, Ford & More
CarMax - Browse used cars and new cars online
Look at the unified front Kevin Leigh's WestHerr.com puts up. Amazing Selection of New and Used cars "FREE TRANSFER to a West Herr facility closer to you." Glad he's not in my back yard 
*thnx Jerry T
