Tesla Motors Inc. will make its first foray toward automated driving, joining luxury rivals in offering high-tech features, including one that can keep the car in its lane, according to a source familiar with the carmaker's plans.

It will announce the plans this week, said the source, who asked not to be identified because the details are not yet public.

Chief Executive Officer Elon Musk posted on Twitter last week that the carmaker will "unveil the D and something else" and included a photo of a darkly lit Tesla and the date Oct. 9.