Please do some investigative work on electric cars before posting about them. You cannot "start an engine" on an electric car. There is no engine! The electric motor doesn't need to "idle" like a regular car, so a non-moving electric car takes little power at all.
Even if the API would support starting the electric car (which it doesn't), the car would sit there with its dash lights on and nothing else -- pulling less than 400W of power. It would take days to run the car's battery out.
Indeed the API does allow for turning on and off the aircon as well as starting (but NOT stopping) battery charging. It does NOT allow for control of steering, brakes, accelerator, or any mission-critical functionality.
That being said, Nissan should have known better. Using the API even returns the owner's email address! Marketers can now abuse this API to get LEAF owner's email addresses. Not cool.
Also, this does not affect the "S" model ("Visia" in the UK) since it does not have cellular connectivity.