The voice-controlled system, currently offered on the latest version of the iPhone but due to be expanded into other Apple devices, will allow drivers to access its functions through a button on the steering wheel using a programme called Eyes Free. 

The driver could then ask the iPhone questions, such as ‘where is the nearest petrol station?’, or ‘call the office’. In effect, the integration of the Siri system will act as a cut-price version of the built-in voice control systems currently offered as expensive options on premium vehicles, such as the Mercedes-Benz COMAND system.

Speaking at the Apple Worldwide Developers’ Conference, the event where Apple launches upgrades for its products every year, the firm’s senior vice-president of iOS software, Scott Forstall, said: ‘A number of auto manufacturers have already committed to deliver eyes-free Siri integration in the next 12 months: BMW, GM, Mercedes, Land Rover, Jaguar, Audi, Toyota, Chrysler and Honda.’

To minimise driver distraction, the phone’s screen won’t light up when it is used. With the Eyes Free feature, the driver can also ask Siri to select and play music through the iPhone’s built-in iPod, hear and compose text messages, use Maps for navigation, find calendar information and add reminders.