Many, many vehicles have real-time fuel-usage meters. Most people completely ignore them. The people who care about fuel-usage -- the sort of person who buys a

Many, many vehicles have real-time fuel-usage meters. Most people completely ignore them. The people who care about fuel-usage -- the sort of person who buys a Prius -- of course pay attention to it because it justifies the reason to buy the car. Yet I suspect that very few of the people who bought the Nest actually care about energy usage, or reducing it. It is a lifestyle product and is a talking point, and while there are some who really desire it for that, many more set it to a static temperature and forget it. I hugely doubt that the total set of Nest users have seen any measurable decline in usage.