Tesla made the first modern electric cars, beginning about 15 years ago. It also made the first electric cars that weren’t focused on being economical or practical cars — as the first electric cars (like the Baker electrics) were designed to be, some 120 years ago. Tesla’s concept was to make electric performance cars — so as to make them exciting cars. But this also made them expensive cars. There’s a new electric performance car on the market — Ford’s Mustang Mach-E — that could steal away some Tesla buyers because it’s a less expensive electric performance car. It also...