Not sure if there is something out there published by GM that gives that information. But if you tell us what area you are from, you can probably get some good recommendations for high volume dealers in your area.
If you are in the Iowa/Midwest area, we bought our Traverse from Karl Chevrolet in Ankeny, IA. They are a top rated dealer in the Midwest.
Can't get a straight answer from a dealer simply by asking and can't tell necessarily by ads - here's a few points indicative of "volume" dealers that hit my marks:
Large number of new vehicles in inventory and more in-transit as checked prior to visit on the Chevrolet website
Ability to take a test drive on a visit without "appointment"
Used car inventory comprised of vehicles they took in-trade from their new car buyers rather than ones purchased at auctions
Large main lot and size of the lot space devoted to new vehicles - large dealers will always have a sufficient stock on main lot and "volume" dealers usually have an "overflow" lot or warehouse.
Number of salesmen's bays/writing stations with telephones and computers in the showroom and the number of salesmen present and available on a good weather weekend. See if they have many of those crapo GM Lucite salesman's awards on their desks.
Number of service advisors and parts department staff
Number of occupied service bays with permanent lifts
Sufficient size waiting room area - equipped with TV, computer stations, free coffee and donuts? - separate equipped kids play room?
Their own automated car wash area instead of using a commercial car wash
tv commercials for the dealer.
and like he said- large overflow lot,
Ordering a vehicle-- does not require a down payment.
and this one is interesting.....When Ive driven in Mexico, I have seen US plated cars- with the same dealers license plate frame I have.... (same place I bought my Traverse, Trailblazer, Impala 07, Impala 10).