The DRIVE - Electric for Gear S2 is now available as a separate app in Galaxy Store. The layout is a little more square due to limitations of the old OS but the functionality is on par with the original DRIVE - Electric. Please read the disclaimer regarding future updates.
If you bought the original DRIVE - Electric before the S2 was discontinued you are entitled to a free voucher for this app. If you have a valid receipt please contact me on PM through my Facebook page and you'll receive the voucher.
Hi. That depends on the usage. Generally the app will only communicate with the car when the app is in the foreground and when the screen is on. In the foreground the app will ping the car every 20 seconds to get fresh values from the car (visualized by the blue transfer icon). This will keep the car awake. Whenever the app enters the background it stops communicating and will also stop battery drainage both on the watch and in the car. Depending on how long the app has been in the background a new wake-up-car routine is called when the app returns to the foreground.
If you choose to activate the Always-On-Display in the app menu, the app will not enter background mode automatically and will continue to communicate with the car. This will cause battery drainage. This option is off by default.
So basically, when the app is in the background it does not drain battery either in the car or on the watch.
Be aware that the app still might end up ranking #1 in the battery drainage list in the Galaxy Wear app. This is because compared to most apps any communication towards external servers is battery intensive for a small watch battery. Most watch apps use a companion app on the mobile that do the actual communication externally. This app is by comparison a stand-alone app and does all the heavy lifting itself, especially in LTE mode.