筛选行为Subject.asObservable()问题

我正在通过HttpClient加载数据并将其发布为:

    export interface Car {
      id:number;
      make: string;
      status: number;
    }

private cars = new BehaviorSubject<Car[]>([]);

constructor( private http: HttpClient) { 
    this.loadCars();
  }

loadCars() {
    this.http.get<Car[]>('/api/cars')
    .subscribe((cars) => this.cars.next(cars));
  }

getFilteredCars() {
   return this.cars.asObservable()
    .pipe(
      map( (cars) => cars.filter( car => car.status === 1)
      )
      );
}

如你所见,我想得到所有状态等于1的车。 当我从我的组件调用它时,我什么都没有得到:

Component

cars: Observable<Car[]>;

  constructor(private carService: CarService) { 
    this.cars = carService.getFilteredCars();
  }

如果返回未过滤的主题,我将毫无问题地获取未过滤的数据:

getFilteredCars() {
       return this.cars.asObservable();
    }

我做错什么了?