Tesla Inc. Chief Executive Elon Musk on Thursday revealed the company’s first all-electric semitrailer truck and a $200,000 super car, his latest attempt to stir excitement for his vision to upend transportation as the company struggles to mass-produce an affordable sedan. The Semi, due out in 2019, is designed to go 500 miles on a single charge, Mr. Musk said. It is also equipped with Tesla’s semiautonomous driving system that will assist drivers and allow the trucks to travel autonomously in convoys with the company’s other big-rigs. In a surprise, Mr. Musk also unveiled Tesla’s newest Roadster, a sports car he said would have a range of 620 miles on a single charge and be available in 2020. The car, Mr. Musk said, will be the quickest production car ever made, going from zero to 60 miles an hour in 1.9 seconds, and topping speeds of 250 miles […]