Why do most EVs use single-speed transmissions?

Most EVs use single-speed transmissions because electric motors have a broad, efficient operating range spanning from 0 to 15,000+ RPM, unlike combustion engines that need multiple gears to stay in their narrow efficient band. Electric motors maintain high efficiency (>90%) across most of their speed range and provide full torque from zero speed. Single-speed simplifies the drivetrain, reduces weight, cost, and complexity, though some high-performance EVs use two-speed gearboxes for top speed.