There are only a few sleeper trains left in Japan and they are what we call cruise trains. These luxury trains are mainly for rich people to enjoy.
この場合、次のような言い方ができますよ。
ーThere are only a few sleeper trains left in Japan and they are what we call cruise trains. These luxury trains are mainly for rich people to enjoy.
「日本にはほんのわずかな寝台列車しか残っておらず、それらはクルーズトレインと呼ばれています。この豪華な列車は主にお金持ちの人たちが楽しむためです」
sleeper trains で「寝台列車」
luxury で「豪華な」
ご参考まで!