The ship was one of the sexiest and most beautiful ones that Random had ever seen. It was astounding. Silver, sleek, ineffable.
(Such as http://starwars.wikia.com/wiki/J-type_327_Nubian_royal_starship)
An RW6 was the sort of thing you only saw in the sort of magazines that were designed to provoke civil unrest.
RW6 was the type of ship that Random Dent used to escape from the planet Lamuella. It was brought onto the planet by Ford Prefect, influenced by the Guide Mark II. Random said in Mostly Harmless/Quintessential Phase that it was the ship she had always wanted.