Along with everyone else, we speculated about what "D" could be and later reported some news, via our contributor Green Car Reports, that "D" is an all-wheel-drive version of Tesla's Model S sedan. An AWD Model S is, by the way, what most people think was hiding behind a black garage door with the letter "D" on it in the photo that Musk included with his tweet.
Screenshot via Twitter
We'll all find out on Thursday when Tesla reveals what "D" is at a media event south of Los Angeles, at SpaceX headquarters (SpaceX is the other company that Musk runs). But here are the top 3 theories:
1. An All-Wheel-Drive Version Of The Model S Motor Authority Green Car Reports located this "D" designated Model S P85, which it thinks is the AWD Tesla.
Said this already. "D" in this theory stands for "Drive" or "Dual" - the latter because in order to give the Model S AWD, Tesla would need to add a second motor to drive the other two wheels. The company has been talking about an AWD Model S for a while and says that the forthcoming Model X SUV will be AWD. Tesla's Fremont factory was recently retooled to build the Model X at the same time as the Models S, so the capability is now there to build the AWD S.
2. An Extended-Range Model S
Steve Burns, the CEO of an electric truck manufacturer in Cincinnati, emailed me after the original Musk tweet and suggested that the timing was interesting: Musk fired off his tweet shortly after General Motors revealed to investors a plan to produce and all-electric Chevrolet with a range of 200 miles for $30,000 - and do it by 2016, prior to Tesla's Model 3 mass-market EV hitting the market. Burns thinks "D" will be a 500-mile-range Tesla, as "D" is actually the roman numeral for "500."
3. A Self-Driving Tesla Google It will a lot sexier than this.
Or maybe a Tesla Model S that just has some level of autonomous-driving technology. Audi and Mercedes recently received permits to test self-driving cars on California roads, as long as insurance requirements are met and there's a qualified, trained employee of the automaker at the wheel to deal with emergencies. Google has been testing self-driving cars for years and is now building its own autonomous vehicles for further experimentation. Musk has said that Teslas will deliver autonomous driving in the near future - but maybe the future is nearer than we think! Morgan Stanley lead auto analysts Adam Jonas has predicted the end of "human driving" and argues that autonomous cars will arrive way ahead of everyone's assumed schedule. Personally, I find this idea intriguing but a bit of a downer if all that's emerging from that cool Tesla Black Garage is an inky Tesla that can "D"-for-Drive-Itself.
For my part, I'm betting that Tesla will unveil a high-performance division - "D" - to compete with BMW's "M" and Mercedes' AMG.
As for the something else, it's probably the Tesla certified pre-owned program that was announced this week. This makes sense as Musk has tweeted tantalizingly before - and then revealed that Tesla's big news is a leasing program.
We'll update Tesla's big secret about "D" as soon as we can on Thursday, so check back.