Ford Motor’s latest offering seems like an oxymoron twice over: It’s a sport utility vehicle that’s electric … that’s a Mustang. It’s also Detroit’s biggest bet yet on a mass-market future for battery-powered cars. The big automakers have been producing hybrid and fully electric vehicles for years. But almost all have been smaller models that found limited demand. Even the manufacturers often referred to them as “compliance cars” — built to help meet environmental regulations while they mainly turned out big internal-combustion vehicles that sold well and made hefty profits. European luxury-car makers like Jaguar, Audi and Mercedes-Benz have added electrified models — all S.U.V.s. Tesla, which has a fervent following, is on track to sell about 360,000 cars this year and is supposed to add a fourth model, a crossover vehicle, next year. But with the Mustang Mach E, unveiled Sunday […]