51-90 points: You are a medium-core libertarian, probably self-consciously so. Your friends probably encourage you to quit talking about your views so much.
Sounds about right. I learned about the quiz through Betsy's Page, and she scored a 40.
These quizzes are fun, and Caplan's is better than average. (My score is probably reasonably accurate.) The Yes-No format, however, can be misleading.
For example, question 45 is "Should the Supreme Court strike down economic regulation as unconstitutional?" However much I may oppose much economic regulation, it strikes me as more of a question about the role of the courts. Whether a too powerful legislature or a too powerful court is a greater threat to liberty is a prudential question, not a question about how libertarian I am.
Or take question 58: "Should the courts be privatized?" I have little difficulty with privatizing civil courts, and in fact, much of their work is already privatized by arbitration. I am less confident about criminal courts. So how do I answer this all or nothing choice?
UPDATE: It turns out my score of 72 is almost identical to Ramesh Ponnuru's (of NRO) 73. Maybe there is something to this test.