Just discovered that Tesla leases their Model S cars: 3 years, 10K miles per year. Sweet. Maybe this is the route we should go until we get the promised 3 - I expect it will be at least 2 years from now. 
My current car and last one were purchased used from dealers, for cash (or essentially cash – for the car I bough recently, I put as much as they would allow on my cash-back credit card, then paid the credit card off immediately, but I got a nice little reward that way; the time before I had one of those 6 month -0- interest offers from my credit card company, so I pretty much used the credit card for the whole amount and took my time paying it off). But the point is the cars were not dealer financed.
I don’t buy cars very often, but both the newer one and the last one were rental returns with roughly 35,000 miles on them, and purchased from dealers who also sold new cars of the same model. No particular reason, but it did mean that the dealer’s service department would be familiar with that car, and I think they have a little bit more incentive to make sure that the car they sell is in good shape, because of brand awareness. But I certainly would have considered other models – I also did pre-shopping online and that was what led me to the respective dealers.
Also, with the most recent purchase, I went into the car dealership during the afternoon on the last day of the month and told the sales rep that I was “just looking” and not ready to buy that day. I got a really good deal – because I had been shopping the car online I knew what was reasonable for that make/year/mileage.