Questions, answered

A Garmin watch Coil works with (below), a Tesla with Phone Key, your Tesla key card, and the Garmin Connect app on your phone for one step of setup.

About five minutes, most of it sitting in the car. Here is every step.

No. Coil adds the watch as one more key. Your phone key and key cards carry on working as before.

One car at a time. To move the watch to another car, choose Set up again in Coil's menu.

Within about 10 metres. The closer you are, the quicker it connects, and the watch tells you when the car is out of reach.

Usually under ten seconds from pressing the button, most of it spent connecting to the car. Once the watch is connected, the next commands are quicker.

Not yet: you press Unlock. To save a step, switch on Unlock when opened in Coil's menu, and opening Coil unlocks the car straight away. Walk-up unlock is on our list.

Not yet. Coil gets you in and works the car's controls, but to drive, the car wants a key it trusts inside: your key card tapped on the console, or your phone. Starting a drive from the watch is on our list.

Yes. Beside the car, Coil uses Bluetooth only. It needs no phone, no internet and no signal, so it works in car parks, garages and at the trailhead.

Yes. Locking, unlocking and the frunk go to the car's security computer, which never sleeps. Climate and charging wake the rest of the car first, which takes a few seconds more.

Coil only uses Bluetooth while it is open. Close it and it stops; the glance shows what the car last reported without connecting.

Coil uses the same system as Tesla's Phone Key. The watch makes its own key and the secret half never leaves it. The car only accepts that key after you tap your key card and press Confirm, and it checks every command Coil sends.

Tesla publishes this protocol for apps like Coil to use.

Remove its key from the car: open Controls, then Locks, find the watch's key and delete it, confirming with your key card. Without the watch, there is nothing else to undo.

Nothing that leaves your watch. The Bluetooth key needs no internet and no account, and without Coil Away, Coil talks only to your car. Our privacy policy has the detail.

No. Coil is an independent app. It works with Tesla's cars and Garmin's watches, and isn't made, sponsored or endorsed by either.

• fēnix 8: 43 mm and 47 mm, 51 mm, 8 Pro (and MicroLED), and 8 Solar in 47 mm and 51 mm
• fēnix 7: 7, 7S and 7X, and their Pro editions, Solar and Sapphire included
• fēnix 9, 47 mm and 51 mm, and fēnix 9 Pro Solar, 47 mm and 51 mm
• epix Pro (Gen 2), 47 mm, and Enduro 3
• Forerunner 265, 955 and 965
• Venu 3
• The twins of those watches: tactix 7 and 8, quatix 7, 7 Pro and 8, and Enduro 2

Coil already runs on many more Garmin watches, from the vívoactive and Venu 4 to the Instinct AMOLED and MARQ, and they're coming in updates. If yours isn't listed, tell us which one you wear.

Teslas with Phone Key: Model 3 and Model Y, Model S and Model X from 2021, and Cybertruck. Coil is built and tested on a Model 3; if yours behaves differently, please tell us.

Coil is free for a day from when your watch becomes a key, so you can try it on your own car. Then it's £9.99 once to unlock it on one watch, or £14.99 for two (in dollars or euros where you pay in those). A licence moves to a new watch whenever you like, and reinstalling Coil never uses one up. Coil Away, for your car from anywhere, will be an optional monthly plan. See pricing.

Email support@coilkey.com and we'll put it right. If you change your mind within 48 hours of buying, we refund you in full. Lost your licence key? We can send it again.