I have found the dealers I have purchased cars from make absolutely no effort to keep in touch with me after purchase. I have been trying to get the dealership that sold me my current vehicle to send me the prorated refund for my GAP Insurance. I paid the car off early and am due a prorated refund per state law. The GAP Insurance company sent me the paperwork needed by the dealership to process the refund. The dealership has been working on it for over a year. I finally spoke to my sales guy, who had no recollection of who I was. I explained who I was, and what was needed, and there has been no communication since then. The General Manager of the dealership was able to get the sales rep to call me, however we are back to square one again. Not very impressive.
I have also had car dealers literally not know who I was mere weeks after buying a car. I will go in for service, wander out on the sales floor, and have the rep that sold me my car approach me and ask if I was in the market for a new car. I will explain that I just bought my car from them a few weeks prior and they act like they have no idea.
Most dealer's don't care about long-term relationships. They want the immediate sale and then you are out of sight, out of mind.
I was in Industrial Sales for my entire career. Long term relationships were CRUCIAL for success. My experience mirrors yours-car dealerships could care less once you roll off their lot with your new/used car.