“D” probably stands for driverless. Or dual-motor. ”Something else” could be either of those—or actually something else completely. Nobody knows for sure, but all will be revealed in a few hours.

Of course, I am referring here to Tesla’s big announcement, expected to happen later tonight, which CEO Elon Musk foreshadowed in a cryptic tweet last week.

There’s also speculation that Musk, in a frenzy of cross-brand promotion, will strap a Tesla onto a SpaceX Falcon 9 rocket and demonstrate the vehicle’s zero-G capabilities and solar recharging panel in orbit. (Actually, I just made that up entirely. There is no such speculation.)

In any case, after some wild initial theories, the balance of opinion among analysts and observers points to dual-motor, or all-wheel-drive version of the Model S being announced. This capability would make the sedan easier to drive in parts of the US with colder weather in the winter months.

But this prediction is not unanimous. One analyst in the driverless camp, Trip Chowdhry of Global Equities Research, claims to have already seen a Tesla Model S fitted out with sensors and cameras in a parking lot near the company’s northern California headquarters (screenshots below).

Trip Chowdhry/Global Equities Research

This could give the Model S autonomous capabilities. Musk has not been shy about his ambitions for self-driving Teslas, telling CNN this week that a Tesla will be 90% autonomous by next year.

Morgan Stanley has been talking for months about the unstoppable rise of autonomous cars (it predicts a self-driving utopia, or complete consumer adoption of self-driving cars, within two decades). Tesla, based in Silicon Valley, with a heavily tech-focused culture, could grasp the opportunity before others do, Morgan Stanley analysts have said.

The ultimate beneficiary of the inexorable shift into self-driving cars might be the companies that make self-driving technology, like Mobileye.

The Israel-based company, which went public in April, makes software and microchips that can be used to help cars avoid collisions. Its technology can detect pedestrians, animals, and debris; as well as lanes (to prevent drifting), street signs, and traffic lights.

At any rate, today’s focus will be on Tesla, which has adroitly managed to build the kind of hype around the announcement usually reserved for Apple product launches. Tonight we will know whether it can live up to that hype.