Overlap Uncovered: Here’s How Much 981 There Is In A Type-991 Porsche 911

The 981 and 991 share a platform

This has been a recurring theme among Porsche sports cars since the 986 Boxster and 996-generation Porsche 911, which shared the 9x6 platform. Then, the 987 Boxster/ Cayman and Porsche 997 shared the same 9x7 modular platform, followed by the 9x1 platform, underpinning the 981 Boxster and 991-generation 911. This theme continues with the Porsche 982 and 992, which are both based on the MMB platform. The principle is the same. In short, the last four generations of Porsche’s mid-engine and rear-engine sports cars were developed as a single platform. The similarities, however, go way beyond that.

The 991 Carrera and 981 Boxster S are especially similar

Both the base-model 991 Carrera and the 981 Boxster S share the same, 3.4-liter engine, making them the most comparable cars of the two model lineups. The mechanicals are, largely the same. The main difference is that the engine in the 981 is turned 180 degrees, in order to work with the car’s mid-engine architecture. This means that, unlike the 911 where the transmission is in front of the engine, the Cayman/ Boxter transmission sits behind the engine.

The PDK automatic is the same in both Porsche sports cars – it is a seven-speed unit, developed with ZF. The only difference here is the differential location, necessitated by the reverse orientation of the transmission. There is a bigger difference between the manual-equipped 981 and 991 since the Boxster uses a six-speed manual while the 911 has a seven-speed unit.

Engine-wise, the MA1, flat-six engine is mechanically-identical in both vehicles. However, Porsche de-tuned the engine slightly for the Boxster S to make it less powerful than what you would find in the 911 Carrera. This comes from a smaller throttle body and different intake and exhaust setups, necessitated by the engine’s reverse position, compared to the 911. It remains to be seen whether Porsche’s 718 Boxster EV will feature an all-new platform or it will be a similar case to the 992.2, powered by Porsche’s new T-Hybrid powertrain.

The Porsche 991 is, actually, no bigger than the 981

While in terms of dimensions, the 911 is noticeably larger, things aren’t necessarily the same in the interior. Sure, the 911’s 2+2 layout makes it more practical, but that’s about it. The dashboard is of equal length and if we don’t count the plethora of optional trim like Alcantara and carbon fiber, the materials are the same. According to Jeff Richardson, who took apart an entire 981 Boxster, the build quality isn’t different either – hardly a surprise given both Porsche models are built on the same production line. Granted, the base 981 uses lower-grade materials in the interior, compared to the more expensive 981s and the 991.

The inner door panels are almost identical, aside from extra trim pieces and a fully leather-wrapped door handle on the 991. Jeff found that everything behind the door card, including the window regulator, door-control unit, and speakers, are identical. The same goes for the side mirrors. Various miscellaneous parts like the A/C condenser, cooling fans, and so on, are also the same. In fact, many of the Porsche 981 parts, feature catalog numbers starting with a "991" prefix instead of "981".

The entire center console is the same in both Porsche sports cars, including the switchgear, infotainment, and various electronics beneath that make them work. The glovebox and trim are also identical. The 911’s signature five-gauge cluster isn’t fully present in the 981. However, the three center gauges are pretty much the same on both models. The 991 and 981 also feature the same steering wheel and seats, although the latter may vary depending on what seats the owner has chosen.

Both the 981 and 991 "think” very similarly too

Every modern car has a high degree of programming involved. Complex codes are written to make all the clever tech work, and in the case of the Porsche 981 and 991, there are plenty of similarities, as shown by Porsche’s Diagnostic System, PIWIS. I will spare you the nerdy part as you can browse through the files yourselves, but essentially, the codes can be found in a common folder, named 9x1, reaffirming that the 981 and 991 were developed as a single platform.

There are some differences, but those mostly concern the different engine and transmission options in both models. The 981 and 991 connections don’t stop with these two models. The Porsche 982 may be on a different platform, but its most radical, road-going variant, the Cayman GT4 RS, utilizes the entire front section of the 991 Carrera.

Is the Porsche 991 a more cost-effective model than the 981?

Surely this is a mistake, right? Not quite. While the 981 is a physically smaller car, the developmental costs associated with both models are very similar. They are also built in the same factory and follow a very similar manufacturing process. However, the difference stems from the models produced, and the 991 was simply produced in greater quantities. During its production cycle, the Porsche 991 was produced in roughly 125,000 copies while approximately 96,000 units of the Porsche 981 were produced.

Essentially, under equal developmental costs, the 911 is the more profitable model since it recuperates the money spent on developing it over a larger production run. Mathematically speaking, the 991 was cheaper to make than the 981. That’s despite the 991 having cost 78 percent more than the 981, over in Australia, as Jeff Richardson reported when both cars were new. But where does this leave you as a buyer, after these findings, would you still splash out on a 991 or save some cash and pretty much get more or less, the same experience with a 981 instead?