SAN FRANCISCO (MarketWatch)—Thursday is Tesla Motors Inc’s “D” day, when CEO Elon Musk will reveal what the “D and something else” is all about.

But one outsider says he got a jump on the electric car maker and has proof D is for driverless.

Trip Chowdhry

That’s one of the photos on Trip Chowdhry’s note Wednesday. Chowdhry, of Global Equities Research, told MarketWatch he spotted the spanking-new Model S car parked near a restaurant in a Fremont, Calif. strip mall, about 3 miles from Tesla’s TSLA, +4.42% factory.

Chowdhry immediately got busy snapping pictures of what he thinks shows a sensor on the front bumper. He said he wasn’t able to talk to the Model S’s owner or driver.

In another photo, this time of the area around the rearview mirror, he shows what he suspects are two cameras and another sensor.

The car was likely made in October, and equipped with the semiautonomous driver-assistance features in anticipation of Thursday’s announcement, the analyst said. He believes the feature will likely be activated over the air, which would be very easy for Tesla to do, after Thursday.

Chowdhry said that the other Tesla surprise for Thursday will be a prototype of the mass-market Model 3, a sedan expected within two to three years. That will be crucial to secure more investments for Tesla’s planned “gigafactory” in northern Nevada, he said.

Tesla has said it needs the battery factory to produce enough, and lower the price of, batteries and make the cheaper Model 3 a reality. The car is expected to cost about $35,000. A Model S sells for about $75,000 and up.

Tesla will also unveil a all-wheel drive version of the Model S, which would be especially attractive to drivers in cold-weather areas in North America, Europe, and beyond, Chowdhry said. At least 80%, maybe more, of Teslas are currently sold in California, Georgia, and Texas, he added.