For 2013, the BMW 5 Series GT lineup gains stop-start ignition and the new Eco Pro system in an effort to increase fuel economy.

Small, medium, large and extra large; these sizes tend to fit a variety of needs. Be it clothing, soft drinks and yes, even cars, most people will find what they need. But what about a half size, perhaps something that slots between large and extra large?

That's the issue we have with the 2013 BMW 5 Series Gran Turismo. It's based on the 7 Series sedan, and features a hatchback body design for more cargo versatility. We're left pondering if this middle ground really needs representation, though, especially when the 5 Series GT costs quite a bit more than BMW's own X5 and X3 crossover SUV models.

The Gran Turismo's dual-mode hatchback is an intriguing model of innovation. From outward appearances, one would assume that access to the cargo hold is just like that of a hatchback, and you'd be correct. The hatch is also hinged at the base of the rear window, however, allowing the tail to be popped open like a conventional trunk. BMWcontends that this allows the passenger compartment to be isolated from the elements when loading standard cargo, with the ability to haul larger items when the need arises.