There has been no official confirmation of what the event is about, but Musk released a torrent of speculation when he tweeted: “about time to unveil the D and something else.”

Tesla Motors Inc (NASDAQ:TSLA) shares surged 4% the day after the tweet, and analysts have been speculating as to exactly what will be unveiled.

Tesla Motors Inc To Unveil All-Wheel-Drive System?

Tesla all-wheel-drive?

At present, Tesla Motors Inc (NASDAQ:TSLA)’s only vehicle, the Model S sedan, is rear-wheel drive. Analysts claim that this has impacted sales in snowier regions and in Europe, and that “the D” refers to a dual-motor, all-wheel-drive system.

Market rivals such as Mercedes Benz and Audi offer all-wheel-drive on their high-end models in the price range of the Tesla Model S ($72,000 to $95,740 before tax credits or rebates)

“If Tesla wants to be seen a true competitor to brands like Audi, BMW, Jaguar and Mercedes-Benz, it needs to offer all-wheel drive,” said Karl Brauer, a senior analyst at Kelley Blue Book.

The company presumably hopes that adding the feature will improve sales. The company sold 13,850 cars in the U.S. through September, a 3% decrease on figures from last year.

Or driver assistance?

Tesla Motors Inc (NASDAQ:TSLA) has already announced that its new Model X crossover will offer an all-wheel-drive system, and upgraded its factory in the San Francisco Bay Area accordingly. The Model S is produced at the same facility, so it is feasible that the system could be added to it.

The Model S has no engine in the front, with the space being used as another trunk, which Tesla calls the “Frunk”. This space could be used to house the second drive unit.

Other analysts have speculated that the “D” actually relates to “driver assist”. Shares in Tesla Motors Inc (NASDAQ:TSLA) supplier Mobileye NV (NYSE:MBLY) also surged on news of the event this Thursday.

The Jerusalem-based company produces anti-collision technology for Tesla, and speculation abounds that the automaker wants to make its first steps towards automated driving. Mobileye predits that it possesses the technology to make this a reality by 2016.