Tesla still swings wildly between profits and losses from quarter to quarter. But sales of its more affordable Model 3 sedan are strong. It was Western Europe’s biggest selling battery car in the first half of 2019. In the U.S., it’s outselling luxury gas-powered competition from BMW, Mercedes, Audi and Lexus. For the past few years, journalists who cover transportation have been wondering: Is this the time that electric cars finally become a major part of the market?