Resale values do have an impact on new car prices. The better a vehicle holds its value the easier it is for the company to charge more for a new car.

Its also worth considering that, for better or worse, very few people actually own their cars today. When you have a loan on it the resale value becomes really important. If the manufacturer wants the kind of customer that buys a new car every few years they'll need resale value that at least keeps up with the principle on the loan over that time.