It's a question that's befuddled many car lovers over the last half-century. Why, knowing what we now know about vehicle dynamics, does Porsche insist on keeping the 911's motor in the rear? Over the years, the recalcitrant behavior this layout was known to cause has been replaced with impeccable manners. Chalk it up to improved body control, stiffer engine mounts, and a reduced polar moment of inertia. Yet, some people feel it's still something of an anachronism.
The skeptics are thrown when they look at a graphic of the Porsche's static weight distribution, but the operative word here is "static." When the 911 shifts weight dramatically under braking or accelerating, that heavy lump over the rear axle helps immensely. As Engineering Explained describes in the footage below, the weight is more evenly spread over all four tires while braking as opposed to a front-engined car, which is part of why the 911 is renowned for its ability to decelerate.
It's well known that the 911, having the rear wheels pressed into the pavement, gives the Porsche the ability to rocket out of the corner like few cars can—even the rear wheel-drive variants. Less known is the way this improves the general efficiency of the powertrain. By moving the motor and the gearbox closer to the driven wheels, the length of the driveshaft(s) are shortened and the drivetrain losses are virtually halved, hence the rumor that Porsche horsepower feels punchier than the rest.
Performance gains aside, the rear-engined design offers a few practical advantages. This layout opens up the cabin of the car, allows for usable back seats, and gives the 911 a surprising amount of leg room, head room, and cargo space despite the short overhangs and the athletic proportions. Make no mistake, this is a major part of why the practical 911 has endured over the years.
Lastly, there's the issue of brand identity. As the Porsche 911 has retained the same silhouette since the sixties, has adhered to a very similar build ethos, and is the rolling epitome of a refined product, moving the motor forwards would taint the car's image. "It's just not the same," the fuddy-duddies would lament upon seeing a 911's motor mounted midship. Some call it stubbornness, some might call it arrogance, but the fact the motor still sits comfortably inside the rear bumper is a testament to the company's insistence on incremental improvements, and a respect for a proud legacy of proving people wrong.