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A new report is adding fuel to the speculation about Apple's plans to get into the auto business.

The website MacRumors reported Friday that Apple has registered the domain names Apple.car, Apple.cars and Apple.auto, though none of the sites is currently active. The registrations are documented on whois.domaintools.com, which keeps track of the people or companies behind Web addresses.

Though it's not known what Apple plans to do with the site names it just registered, the company is in the midst of developing a number of auto-related projects.

Apple's CarPlay system, rolling out in some major auto models this year, lets you sync your car with your smartphone and control functions such as texting, navigation and music via voice command or by using the touch screens or steering-wheel buttons in your car.

More ambitiously, the company is reported to be working on its own Apple Car, an electric vehicle that could debut in 2019. The project, code-named Titan, is cloaked in secrecy, but Apple recently hired a top Mercedes-Benz research and development executive to help push it forward.

This story originally posted as "New clue about Apple Car plans" on CBSNews.com.