The hypothetical scenario stipulates that the illusion is perfect so long as you're driving the car. That may be an unrealistically difficult goal to achieve, but if you take its success as given, it means that the illusion really is as good as the true thing... so long as the illusion is never pierced. The problem, of course, is that with a car the illusion would be all too easy to pierce; just pop the hood. Even if the actual goal is not to drive an internal combustion car but merely to *believe" you drive such a car, one glance beneath the hood (or having once been told the truth) still means a loss of value.