A new spot from the General Motors brand and director Jason Reitman features a gang of age-ambiguous young couples—are they teens? twentysomethings?—arriving in their ride at some middle-of-nowhere lake, where they strip to their skivvies and dash into the water. After a playful bout of splashing and holding hands, etc., they emerge, shivering, to discover that the driver has accidentally locked his keys in the car. Panic? Nope. Chevy’s mobile app lets him use his smartphone as a backup remote, popping open the doors by tapping his touch screen. “From close call to best night ever,” assures the voiceover. Crisis averted….