The MX-5 Miata is as uncomplicated and pure as a sports car can get. Since the two-seater entered the marketplace more than 20 years ago, the MX-5 has defied the convention that sports cars, particularly convertibles, were pricey, unattainable flights of fancy reserved for those with deep pockets. But enthusiasts come in all shapes, all ages, and with a variety of pocket sizes so it's no wonder that with more than 900,000 units sold, the MX-5...