Until someone gamifies car purchasing, so that when I get 10,000 facebook points, I can redeem for a discount at my local GM dealership. Now that would be a great source of leads for car manufacturers.
I would love to decouple the showroom (sitting in the car, test drive, whatever) from the dealership. If a car manufacturer were to create a space were I could spend some quality time with the car without any threat of encountering a commissioned dealer, I would love it.
Then, I can choose where and how I buy the car later. The manufacturer would benefit from this no matter how I buy the car. Keeping these "shark-free-showrooms" stocked with demo cars, coffee, pastries, and branded swag would just be a general marketing expense.