Tesla Motors Inc. Chief Executive Officer Elon Musk said within two years a customer would be able to summon an electric car to drive autonomously from Los Angeles to New York.

"I might be slightly optimistic on that, but I don't think significantly optimistic that we can do that in two years," Musk said in a press conference on Sunday. He added that it should be technically feasible to have fully autonomous vehicles within 24 to 36 months.

The comments come after the company announced a software upgrade that will enable owners of Model S sedans to park them in a garage or in perpendicular spaces without a driver at the wheel. Musk called this a "baby step" in the development of driver-less cars.

Owners of Model S sedans will be able to park them while standing outside the vehicle if it's within 33 feet (10 meters) of a garage or narrow space, Tesla said on the eve of the Detroit auto show. The cars can also be summoned from a parking spot, according to the company, which said the tools remain in a beta, or test, version. Model X owners will have the capability in a few weeks, spokeswoman Khobi Brooklyn said in an e-mailed statement.