Hybrid or hatchback? Value-driven commuter or fun-to-drive compact? These are the choices confronting shoppers of two of the most popular and engaging compact sedans, in the Hyundai Elantra and the Mazda 3. Most models come as compact four-doors, but the Mazda 3 can be optioned as a hatchback with a powerful turbocharged engine. Hyundai swings the...