All-electric vehicle maker Rivian is dealing with a lot: the end of federal support for EVs, a surge in hybrid vehicle sales and a rate of cash burn that still alarms investors, among other things. The company also has relatively low production and delivery numbers , but Rivian CEO RJ Scaringe told CNBC in a December interview that's not the full story. "The R1 is the best-selling premium electric SUV in the United States," he said, adding that it has been a top-selling premium SUV of any kind