Tinjuan yuridis terhadap praktik promosi dalam bentuk brosur kendaraan bermotor berdasarkan hukum perlindungan konsumen : studi kasus gugat Ludmilla Arief melawan PT. Nissan Motor Indonesia di BPSK provinsi DKI Jakarta = Juridical review of promotion pracitice through brochure of motor vehicles by law of consumer protection : case study the lawsuit by Ludmilla Arief against PT. Nissan Motor in BPSK DKI Jakarta