The initial Tesla Roadster put the all-electric manufacturer on the map, even if most Model S and Model X customers don't remember it. Slated to begin its return in 2021, the second-generation Roadster bests it, predecessor, by appending two small rear seats, a significantly longer driving range and a much higher level of performance. Tesla CEO Elon Musk bragged about a 1.9-second 60-mph time and a 250-mph top speed when the Roadster concept was uncovered back in 2017. Tesla declares it will offer the base…