The biggest giveaway is on the rear door's cutline. A normal F-Pace's shut line runs right into the middle of the rear wheel arch. But on this mule, the door closes well forward of the arch. Outside the axles, Jag has stretched the front overhang – it's far more prominent with a completely different lower intake – and the super-short rear overhang reinforces the idea that we're seeing a longer platform.
While we know the wheelbase is longer than the normal F-Pace, the platform underpinning this mule could go one of three ways. First, in what would probably be the most cost-effective route, Jaguar could simply stretch the chassis underpinning the F-Pace. Second, Jag could mine the Land Rover parts bin for a fullsize platform, perhaps from the Range Rover. It's not a crazy idea, and would open the J-Pace to a more potent line of powertrains – hello 5.0-liter, supercharged V8. Finally, the J-Pace could borrow its platform from the XJ sedan.
One reason this mule could be riding on a Land Rover platform is because of its powertrain. According to the vehicle lookup on the British Ministry of Transport's website – see the final slide in our gallery above – the mule's number plates belong to a vehicle with a 2.0-liter turbodiesel engine and an electric motor, a diesel hybrid. The fullsize Range Rover is available in such a configuration outside the US, but it uses a 3.0-liter V6.
Clearly, the J-Pace is still very early in its development process. That means we shouldn't count on seeing a production-ready vehicle for quite some time. Our spies point to a 2019 debut as a 2020 model. We'll just have to wait and see.