This product plan has many positive aspects from the manufacturers point of view. For one, each model line has multiple variants that enable the manufacturer to compete strategically in the marketplace by filling multiple niches and price points. For example, one might compare a base Panamera against cars such as the 7 series, A8, XJ, and others. On the other hand, the range topping Panamera Turbo S competes with the likes of the Rapide and Continental Flying Spur. Not simply is the same model line able to compete across various segments, but Porsche is able to do it at a significant cost savings. Rather then engineering a complete new platform, only specific components are changed along with equipment either added, taken away, or modified. That being said, the amount of variation can be minor such as the difference between a base Carrera and a Carrera Black Edition, or on the extreme side, the difference between a base Carrera and a GT2RS. Despite the extreme differences of the latter two cars, they still use the same platform and have many other components in common, therefore increasing profitability while offering the consumer completely different characteristics.
This formula seems to have worked for Porsche. Instead of the "one-size fits all" philosophy, the customer has the choice, allowing more individual specifications. By having multiple engine options, Porsche can cater to a broader variety of customers. The same goes for the ability to choose from rear or four-wheel drive, in which buyers usually select based off of their geographical location. Last, the purpose of the car can be altered through different variants such as the choice of a cabriolet or coupe, or a more enthusiast focused version such as a the "R", "Spyder", or "GT" trims.
As previously mentioned, the greatest number of new variants appear at the end of a models life cycle. This builds some excitement around a product that has had its sales decline due to age. In turn, this allows Porsche to sell a last few cars and extract some final profits from the aging model.
From the consumer perspective it is both good and bad. Good in the sense that there is a lot of choice and that you truly pay for exactly what you want to drive. A basic model will cost a lot less then a top spec loaded car. So depending on which model one is looking for, their product strategy could potentially offer an advantage.
Over the years the number of variants has continued to grow. As a result, at the end of the model run of the recently introduced 991, don't be surprised to see Porsche create over 30 variants.!