iPhone Digital Key: If the battery dies you have 5 hours to unlock your car

Apple's Digital Key system will keep working even after the iPhone's battery runs out, though users will only have a few hours to get back to their vehicle. While only one car was confirmed during the streaming WWDC 2020 keynote today with Digital Key support today, in fact there are a lot more to look forward to – and some provisos to the system.

Digital Key builds on the NFC access system we've seen used from some automakers in recent years, bypassing traditional keys and instead using fobs or keycards. Introduced alongside iOS 14, the system allows an iPhone to unlock the vehicle's doors and start the ignition.

It also enables easier key sharing and driver controls. Up to five contacts can be granted access through iMessage, and each Digital Key can come with preconfigured options that apply limits for things like top speed, total available horsepower, maximum radio volume, traction control settings, and more, model depending. Owners will be able to revoke key access easily, too. As well as saving the Digital Key to the iPhone's Apple Wallet, it'll also be available through Apple Watch.

Of course, one thing you usually don't have to worry about with your traditional car keys is running low on battery. Should your iPhone run out of charge, Digital Key functionality will still be available, Apple says. A power reserve feature will allow it to open the doors for up to five hours – model depending – even if the iPhone itself won't turn on because of insufficient charge, though if you turn your iPhone off manually it'll only unlock the car when you switch it back on fully.

First out of the gate with iPhone Digital Key functionality will be BMW, and specifically the 2021 5 Series. Announced earlier this year, the new luxury sedan saw BMW, Apple, and the Car Connectivity Consortium to make sure it was set up to using an iPhone as its key from the outset. For now, that means the Digital Key 2.0 specification, which allows for NFC unlocking when you bring the phone within 1.5 inches from the driver's side door handle, and then starting the engine when the iPhone is placed on a reader or wireless charger in the cabin.

By default, "Express Mode" is set as active. That doesn't require that the iPhone is unlocked in order to open the car and start the engine. Optionally, you can disable that, in which case you'd need to first use Face ID, Touch ID, or your passcode to unlock the iPhone before it would work as your key.

The next spec – Digital Key using Ultra Wideband – hasn't been finalized yet, though that could drop as soon as next year. At that point, Apple's U1 Ultra Wideband chip, found in its recent iPhone models, will come into play. You'll be able to leave the handset in your pocket or bag, and still have it unlock the car.

While it may start with the new 5 Series, that won't be the end of it. In fact, BMW says, a huge number of its models – including the 1, 2, 3, 4, 5, 6, 8, X5, X6, X7, X5M, X6M, and Z4 – will support Digital Key, as long as they were manufactured after July 1st, 2020. You'll need an iPhone XR, iPhone XS, iPhone XS Max, iPhone 11, iPhone 11 Pro, iPhone 11 Pro Max, or iPhone SE (2nd generation), or an Apple Watch Series 5. Digital Key will require the upcoming iOS 13.6 and WatchOS 6.2.8, too.

Only one iPhone will work as the primary key. Each person – the owner, and up to five invited drivers – can activate an Apple Watch too, which is linked as an alternative key. If you don't have access to your iPhone, meanwhile, and you want to control who can unlock the car, there'll be a new Digital Key menu in the BMW's infotainment system.