Here's an example of the Mercedes-Benz 'Autohaus' showroom design in Bellevue, Wash. I assume this will be configured to front the street to some extent on the site at Hampton, Clayton, and Berthold avenues:
And here is Isringhausen Mercedes-Benz in downtown Springfield, Illinois. The structure was built in the late 1980s and renovated two years ago. The blue exterior elements and signage were added as part of the Autohaus Project, and the interior was renovated extensively, but the exterior was otherwise unaltered.
As you can see, it is built up to the sidewalk along Jefferson Avenue, and it connects to adjacent Porsche (Jefferson Avenue at Second Street) and BMW (Madison Avenue at Second Street) showrooms that are much more modern in outward appearance and not quite as well oriented to the street as the M-B showroom. It's a really nice complex, though, and it really anchors that part of Downtown Springfield well even with two surface lots for new and pre-owned inventory.
For the new Tri-Star showroom, I expect there may be a small asphalt lot to display some new cars, but the bulk of inventory and/or cars in for service will probably be in the parking structure, not unlike the current Mini of St. Louis showroom (which, oddly enough, will be replaced with a more sprawling complex in Maplewood soon).