Composition Delegation Binding Bug

class Engine {
  constructor() {
    this.running = false;
  }
  start() {
    this.running = true;
    return 'Engine started';
  }
}

class Car {
  constructor() {
    this.engine = new Engine();
    // expose the engine capability via composition
    this.start = this.engine.start;
  }
  drive() {
    const msg = this.start();
    return `${msg} | engine.running=${this.engine.running}`;
  }
}

const car = new Car();
console.log(car.drive());
// Expected: 'Engine started | engine.running=true'