The development of the Porsche 996 series – the internal designation “996” represents all Porsche 911 models built between 1998 and 2004 – ment the furthest reaching evolution of the 911 concept since its introduction in 1963. The 996 was the successor of the 993, it may only be considered as a formal successor due to the revolutionary changes implemented with the 996 evolution.
The exterior underwent a complete and radical redesign: The dimensions and cabin design of the old 911 (allowing flexible conversions between all pre 996 models forth and back) was abandoned, the 996 became both longer and wider than its predecessors transforming it more into a comfortable GT kind of car compared to the earlier compact and spartanic 911s. Also the rest of the bodywork was changed in every aspect: The 996 received new front and rear bumpers and basically everything in between. The typical and infamous waist of the 993 was not carried on to the 996, its fenders no longer were wide and curved, a softer, rectilineal and more neutral design was chosen. Both windshield and front lights were less steeply raked and the entire design was becoming more rounded off and softer. The 996 also got new headlights and rear lights, the “fried egg” headlights were directly adopted from the 986 Boxster making it hard to distinguish the 911 from the base model Boxster. The design of the new 996 was deceiving to most enthusiasts as most of the old and true 911’s spirit was lost. However, from an engineering and a comfort perspective the new design was more beneficial both providing improved aerodynamics (993 Carrera CW 0.33, 996 Carrera CW 0.3) and more space in the interior.
Technical innovations included the second revolution within the evolution from the 993 to the 996: the switch from air-cooled to water cooled engines. Various reasons forced Porsche to make this strategic decision, the most prominent was that it had become increasingly difficult to meet ever stricter emissions and in particular noise regulations with an air-cooled engine. In addition, Porsche had no choice but to step up to 4-valve cylinder heads to maintain a competitive power to volume ratio, as the experiences with various racing engines and with the Porsche 959 showed that 4-valve technology would only be feasible with water cooling. Again, from on engineering perspective this decision is efficient and promising but switching to water cooling also ment that the infamous and unique sound of the classic 911 would disappear:
This sound was created on one hand by the large cooling fan and on the other hand by the engine noise itself which could easily escape through the thin and cylinder walls (not surrounded by water), both sound effects were eliminated. Water does have a much higher thermal conductivity than air but due to its higher density (combined with the thicker cylinder block walls) it also absorbs noise much better. These factors lead to the fact that the typical sound of the classic 911 that survived for 35 years would now disappear. Porsche invested serious research and development to conserve the classic sound when switching to water cooled engines by producing it synthetically via sound-engineering but from an enthusiasts perspective they did not succeed.
All Carrera models received a new developed water-cooled 3.4 litre flat-six engine which except for the configuration did not share any parallels with the M64 engines. This engine turned out to be an imperfect powerplant, one problem being leaking crank shaft seals and on the other hand lubrication issues leading to engine failures causing sensitive replacement-on warranty actions. Porsche revised the engine and upgraded it to 3.6 litres and resolved most of the problems in 2001.
In contrary 996 Turbo, GT2 and GT3 were fitted with a very reliable and solid watercooled evolution of the proven M64 engine featuring dry sump lubrication using an external oil tank and not suffering of any of the above problems.
The 996 interior also was subject to a major redesign. The instrument panel no longer was designed as a set of independently positioned instruments but now a cluster of 5 instruments, 4 of them interlaced towards the center, with the rpm meter as the largest instrument in the center. Also the center console and the door cards were redesigned and the design of all interior components was matched to each other. The only items that remained nearly unchanged were the seats.
The interior had become more comfortable and suitable for the use as daily driver. Numerous items that were offered optionally for the 993 series become standard equipment in the 996. ESP and Navigation system were added as new options.
The 996 Carrera and the 996 Carrera 4 are the “base-models” of the 996 generation. The Carrera was the rear-wheel drive and the Carrera 4 the all-wheel drive version. Besides these differences regarding the powertrain the models were equal to the greatest extent.
The Carrera models were equipped with the new developed 3.4 litre powerplant (300bhp @ 6800rpm and 350Nm @ 4600rpm), did the standard sprint from a standstill to 100km/h in 5.4s and reached a topspeed of 280km/h. After numerous problems with this engine (cf. above) an improved version of it also featuring increased displacement to 3.6l was released for all Carrera models in 2001. Producing an extra 20bhp and 20Nm at the same rpm levels performance improved to 5.0s and 285km/h.
As a reaction to the criticism that the 911 front may not be distinguished from the 986 Boxster, Porsche in 2002 performed a minor re-styling of the standard models which included switching to the Turbo Style headlamps and a new front bumper. These were sometimes known as the Mk. II generation of the 996.