Naturally, as with all things, as technology gets more advanced, the cost of producing cars will diminish. This invariably means that the price of cars, or at least the price for the equivalent car, should come down. This is a wonderful theory, and quite solid, however in practice this is far from the truth.
The reality of the situation, is that car as technology improves, cars improve. You may be getting a lot more for your buck, relatively speaking, but you will still be paying the same, albeit inflated, price for your vehicle.
So, while we like to dream that one day the price of cars will drop so that we can all afford the cheap cars of our dreams, until such time as some new transport technology replaces the car, it looks very likely that the relative price of buying a car will stay very constant.