If you’re lucky enough to consider a summer toy, Mazda’s been tempting shoppers with this one for 3 decades. Of course, it’s the Miata; the world’s fun-loving, affordable roadster. The weather is warming up and top down driving is on your mind. But the dwindling 2-seat convertible segment is typically reserved for the wealthy. No worries; the Miata and its Fiat 124 Spider counterpart are the least expensive new roadsters …