The phrase "land yacht" refers to a very large and luxurious vehicle that travels on land. It's like a fancy and spacious version of a car or RV. Full definition
I called the previous concept a «massive, luxurious land yacht,» and I stand by that description. (theverge.com)
Higher gas prices and sagging demand for land yachts have hurt GM, perhaps more than Ford and Dodge. (articles.orlandosentinel.com)
In a few words, Diplomat is a traditional American land yacht, with the blessings and the curses inherent to that class of car. (articles.orlandosentinel.com)