Tesla Motors founder Elon Musk started a flurry of speculation on Wednesday after saying it is "about time to unveil the D and something else", with an accompanying photo mentioning the upcoming date of Oct. 9.
It wasn't immediately what either the "D" or "something else" referred to, but the electric car maker has been widely expected to reveal more details soon on its next car model, which is believed to be the first small sedan aimed at the normal car-buying public.
Currently, the company offers a high-end sports coupe called the Model S, and a forthcoming SUV — the Model X — with base model prices starting at about $70,000 US each.
Musk added more fuel to the speculative fire later in the day when he tweeted that the wording of his original tweet was unintentional, but adding "Glad I didn't mention the other letter."
Tesla is believed to be working on an all-electric car that would be more affordable.
Tesla's shares gained about three per cent on the news to trade at $246.38. The stock is up about 60 per cent so far this year, after more than quadrupling in value in 2013.