Book by Cadillac, the luxury brand's car subscription service, will shut down effective Dec. 1. The Wall Street Journal first reported on the subscription service's end and cited ongoing challenges for the program's demise.

Motor Authority reached out to Cadillac for additional information on the program's end and a spokesperson said in an email, "Cadillac will temporarily pause the Book by Cadillac program. Book by Cadillac launched as a pilot program, providing the brand with valuable insights and contributing to Cadillac’s ongoing commitment in identifying new and innovative luxury experiences for their customers. The brand will use these insights to make adjustments to the Book by Cadillac strategy moving forward. Additional details will be made available at a later date."

Book by Cadillac launched in 2017 in New York City and offered members the chance to swap into numerous Cadillac vehicles at a fixed price 18 times per year. For $1,800, members received white-glove delivery, insurance, unlimited miles, maintenance, and detailing services. According to the WSJ, many facets proved more costly than previously imagined. It's also fair to point out Book by Cadillac launched as a pilot program in NYC and expanded once to service Los Angeles and Dallas.

Sources familiar with the program told The Wall Street Journal that the support technology to run Book by Cadillac was tedious and time-consuming, which added cost to the program. Additionally, having a fleet of cars changing hands often required more maintenance, repairs, and cleaning, especially when the cars were to be shipped out again in as little as 24 hours. Again, these factors added cost.

Scaling such a service for more markets could have been too costly for Cadillac and parent automaker General Motors to swallow at this time. The brand's official statement does hint we'll see a Cadillac car-subscription service of some sort return at some point, however.

Cadillac was first to introduce the concept of car subscriptions, but numerous rivals climbed aboard the bandwagon. Since Book's launch, Porsche launched Passport, Volvo introduced Care by Volvo, Access by BMW debuted, and Mercedes-Benz Collection launched.

And Book's cancellation comes as the brand begins the process of packing up its New York City headquarters and relocating back to Michigan under new president Steve Carlisle. The end of Book is yet another drastic change we've seen at Cadillac since GM ousted former president Johan de Nysschen this past April.