Elon Musk just sent out this cryptic tweet and teaser image of what may be a modified Model S that's due to be revealed on October 9. And he's hinting at something else. Maybe that upgraded Roadster we've been promised? Let the speculation begin...

And let the jokes commence...

UPDATE: The smart money is on an all-wheel-drive Model S. The D could stand for Dual motor, and with the AWD Model X on the way – using the S platform – it won't take much to adapt the new drivetrain to the sedan. It's also been hinted at in the past.

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