TBH the ones for newer cars are not vastly useful, since so much needs specialist tools or PC's to do. The older ones are great, and those for the Capri Mk1-3 are useful, likewise for the Volvo 240.
The recent one for the VW T5 was not much help, and the internet proved far more valuable. Add that to the fact that cars are a disposable item for many nowadays and I can understand the loss of demand.
Hopefully they keep up the novelty stuff though, their baby manual was funny, and the Spitfire one interesting.