Great Topic and just what we need to get back into focus here on DR.

Thanks Alex
I'm going to speak as if I was still at my previous single point Mercedes dealer for the sake reference. Then I'll get to the more serious stuff.
I'll talk used cars here to begin with.
I knew each and every single used car on the lot inside and out. Many times I was the one taking the photos and this was an excellent opportunity to get more acquainted with each vehicle.
First, I would hunt out the window sticker. If I had the window sticker, I was golden because I could then copy over the option codes into Homenet. If I didnt have a window sticker I would print out the available options for that vehicle and while sitting in the car try to pinpoint which options or packages that vehicle had. If time permitted I would take the car for a quick drive as well (If I was not the one that appraised it) Yes it took time and yes I know this is a much more difficult task with a higher volume store.
Returning the to vehicle edit page in Homenet (I'm not plugging Homenet but it's what I used) I could choose the exact options each vehicle was equipped with. These options would then save into the "Uncategorized Standard Equipment" field (this is the field that is exported by default to your site and other 3rd party sites). I would then get a copy of the CarFax - 1 OWNER, if it was a used Benz I would get a copy of the service history as well.
This is the information I would use to merchandise the vehicle. It's NO DOUBT a hands on process and you have to WANT to do it. This is where it usually falls short at most dealers.
At times I would have someone else take the photos of the car and I would do my best to write the description with out touching the car but I was surly going to miss out something that I could say about that car that would in return add some value.
Don't forget your photos can help showcase the options as well. I would always take photo of the Navigation, Sunroof, Automatic Trunk open button, etc and of course the window sticker if I had it etc.
As for SEO value. I did have AAN (drivemb.com) build the site so each vehicle was on a page that would index. It would grab the vital vehicle information and dynamically generate the URL string and title tag and with time I wanted to take this a few steps deeper but never got to it.
Example:
http://drivemb.com/2008-mercedes-benz-e-class-e350-4matic-sedan-c-1726.htm
Did this work? Yes, it did..there were several times I would do some long tail searches to find my inventory pages in there. Once I had traded on a Toyota and it was showing up before the sister toyota dealers website for some relevant keywords. Plus the analytics was telling me the story as well. That really is another subject though.
Back on subject..
Why has no one built the right relationships with the manufacturers to get VIN to option/package/color specific decoding? Anyone?? We have to be able to establish a standard across the industry for this.
Actually Homenet was on right track with Mercedes. They dial into the Mercedes Vista inventory system and extracts exact options and packages for used Mercedes as far back as I believe 2002. You still have to manually bring this information over from the "other" tab into the vehicle details/comments but all the accurate information is there. Why can't we do this with all the manufactures?
Can you imagine the power this company would have with detailed VIN explosion down to the exact options/packages and colors. I realize this would never be 100% (dealer installed options and Ford and Fleet vehicles would be a monkey wrench) but it would be a huge benefit.
In regards to DMS >> Homenet (or any other inventory program and can read the manufacture codes) I've been quite successful USING BOTH ADP and Reynolds. From my experience, as long as you can get who ever is entering the new car information into the DMS trained to do it accurately most inventory systems can match this information in their system. I do believe there are different levels/upgrades with in the inventory modules that could be a baring factor on this.
What about full online transaction? We will need to get way better with our data before this move to the next step.