Despite on-again rumors , this latest set of spy shots seems to indicate that yes, a five-door Subaru WRX is indeed in the works. Subtlety is key with this test mule, but there are clear bits of evidence that indicate a hotter hatchback is what's being developed here.First, notice the WRX-spec front fascia grafted onto this ordinary-looking Impreza hatch. From there, we can clearly see the tiny bit of added width – most obvious on the roof and at the rear, near the fuel door and taillamps. And of course, let's not forget about that bulge in the hood, consisting of a metal panel that covers the hood scoop and can apparently be removed thanks to a series of screws, according to our spies. The WRX's more robust exhaust and larger wheel/tire package have not been added to this mule, though we're told that this is commonplace for Subaru prototypes – those bits should be added on as the car's development progresses.We fully expect a WRX hatchback to be, well, just that – mechanically, it should be identical to the sedan brethren, though our spies indicate that Subaru could be testing an updated version of the WRX-spec boxer engine. Of course, there's always a chance that this could be something else entirely, given the on-and-off reports of the five-door 'Rex's existence in the first place...