Not sure what Martin thinks

But I’ll tell you what my “car guy” husband thinks and it’s probably not necessarily what Martin would say (he sold cars for a number of years, honestly, and now works for a car manufacturer in customer care. He is upfront about what car salesmen and dealers do and do not make money on (ps…yes, there are often “shady” car salesmen, but more often than not, the dealership owner and managers are the ones making the big bucks or pushing anything dishonest…your car salesman is making diddly squat and just trying to squeak by — it’s why my husband left that aspect the business, even though he loves it)
Ok! He says:

I believe in them, so long as the plan purchased is backed by the manufacturer, and that it’s purchased at the time of sale. Otherwise, the price goes up as it’s now a used vehicle. I would especially recommend one on a used car with higher mileage. It will cost some cash, but may be worth it in the long run. Make sure you’re purchasing the level of coverage you want. Not all plans cover the same components, and some have drastic levels of coverage (not much to everything). A customer can shop around for pricing, which can be used to negotiate. Most dealers mark up the plans between 75 and 100-percent from cost + offer payday loans (easy&fast cash). It’s a huge moneymaker for most dealerships.

What I don’t suggest are the following:
-tire & wheel care
-paint and fabric protection
-LoJack (insure your vehicle)
-key care