Unless Apple has discovered something completely new about storing energy, that no other battery manufacture has figured out, or figured out how to do economically, this vehicle will have the exact same limitations that e-vehicles have, including limited range and quick drains in cold weather.
What Apple may be doing is building a research vehicle to test various sensors, interior displays and autonomous driving ability, but is based on an existing platform. They could easily work with either BMW or Mercedes-Benz--both of which have research labs in Silicon Valley not far from Apple--to build such a test vehicle.
The Chrysler minivans running around Silicon Valley are in effect the earliest technology demonstrators, since the hardware needed is so bulky based on the state of current technology. It's possible Apple will be able to reduce the size of the hardware so it could fit something like the BMW 2-Series Active Tourer or Mercedes-Benz B-Class hatchback--and could show it off possibly as early as the Los Angeles Auto Show this coming November.