Tesla Motors Chief Product Architect Elon Musk teased his followers on Twitter Thursday about an upcoming new vehicle from the company only labeled as 'the D.'

With the caption "About time to unveil the D and something else" and a photo of a vehicle seemingly similar to Tesla's Model S under a half-open garage door with a huge 'D' on it, Musk's cryptic message sent the company's stock market value to almost 5 percent higher on Thursday with the stock closing at $251.42.

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Aside from stocks, speculations were also raised, especially after Tesla Motors sent official invites to the press about an event on October 9 in Los Angeles which has been assumed to be related to the teasing Tweet.

According to the Daily Tech, the 'D' in Musk's Tweet may stand for "dual motors" and could be a reference to an all-wheel drive (AWD) version of Tesla Motors' Model S.

Tesla's Model S sedan, as well as the upcoming Model X, both have a space in the front trunk for a second electric motor.

Others contemplated that the 'D' probably stands for "Driver Assistance" which had been linked to newer Tesla software, according to Electrek's Seth Weintraub.

To make it more interesting, Tesla's spokesperson Simon Sproule refused to give further details about the Tweet and declared that all will be revealed during the event this coming Thursday.

Meanwhile, car enthusiasts and analysts continue to speculate on the big surprise Musk is teasing the automobile industry about.

"The D stands for drop top," Ascendiant Capital Markets analyst Theo O'Neill stated, suggesting that the new vehicle is a convertible since Huntington Beach-based Newport Convertible Engineering recently customized the first Tesla Model S into a convertible.

"Could it stand for delivery? I think it could be a small pickup or delivery truck. Elon mentioned a truck several months ago, and a lot of people blew that off. But the truck market is very dynamic right now; volumes are high, and there are a lot of new models on the market," Kelley Blue Book senior analyst Karl Brauer stated, adding that having an electric pick-up truck would be most helpful to small business owners.

Others, especially current Model S owners, are watching out for its AWD version with some citing that it is a must-have.

Amidst all the speculation, Musk Tweeted another teasing message and made no further comments on the issue.

Tagstesla motors, Elon Musk, Tweet, surprise, Model S, Model X, 'the D'