Apple, whose CarPlay interface is used by millions of motorists to control music, get directions and make phone calls, is looking to expand its control in cars.The company is working on technology that would access functions such as the climate control system, the speedometer, the radio and the seats, according to people familiar with the effort.The initiative, known internally as Iron Heart, is still in its early stages and will require cooperation from the automakers.These efforts underscore the idea that cars can be a huge profit for the tech giant even without selling the cars themselves. While Apple’s car-making plans have run into hurdles, including a defection from top executives this year, the company has continued to make progress with CarPlay, which allows customers to connect their iPhones to the car to engage with so-called infotainment features. Seven years after its release, it is currently used by most major automakers.