tl;dr Spend money while building a mutually beneficial relationship.
Here is the acronym presented in the video which describes the four ways of building that relationship:
L - loyalty: within a brand, stick with a dealer.
O - options: almost pure profit for dealers and factory.
V - volume: buy lots of cars; if the dealer needs to move a particular model, do not say no!
E - events: attend events, such as hospitality, racing schools, etc.