this.vehiclesService.create(vehicle)
  .flatMap(v => {
    this.vehicle = Object.assign(new Vehicle(), v);
    const vehiclesimages: Observable<any>[] = [];
    this.images.forEach(image => {
        const vimage: IVehicleImage = {
          id: null,
          image: image.file,
          vehicle: this.vehicle.id
        };
        const ovimage = this.vehicleimageService.create(vimage);
        vehiclesimages.push(ovimage);
    });
    return ObservableRx.merge(vehiclesimages);
  })
  .subscribe(
    (data) => {
      // return the Observable Object, it didn't work
    },
    (error) => {
      // error
    },
    () => {
      // complete
    }
  );