Tesla chief executive Elon Musk is hinting about a big product revelation coming up next week. In a tweet on Thursday, Musk posted a photo of a partially-revealed car along with the caption, 'About time to unveil the D and something else.' The company will debut the new products on October 9. According to speculation, the Tesla 'D' may be a lower-cost electric vehicle sedan, a departure from the Model S, which has a starting price tag of $71,000, and the upcoming Model X. Musk has also previously hinted at an SUV smaller than the Model X. Other theories say the 'D' might not refer to an actual vehicle, but vehicle technology.