The Porsche 928 is a grand touring car which was manufactured and marketed by Porsche AG of Germany from 1977 to 1995 across a single generation with an intermediate facelift. It is a 2+2 coupé with a rear hatchback. The 928 has a water-cooled engine which is mounted in the front and drives the rear wheels. It was Porsche's first production car with a V8 engine.
Initially conceived to address changes in the automotive market, it represented Porsche's first fully in-house design for a production vehicle and was intended to potentially replace the Porsche 911 as the company's flagship model. The 928 aimed to blend the performance and handling characteristics of a sports car with the comfort, spaciousness, and ride quality of a luxury car. Porsche executives believed that the 928 would have broader appeal compared to the compact, somewhat outdated, and slow-selling air-cooled 911.
The 928 earned recognition upon its 1978 release by winning the European Car of the Year award, one of the few occasions that the prize did not go to a mass-produced family car.
Conception In the late 1960s, Porsche had solidified its reputation as a manufacturer of high-performance sports cars. Amidst the 1970s oil crisis, there were discussions among executives regarding the potential addition of a more fuel-efficient luxury touring car to the company's lineup. Managing director Ernst Fuhrmann advocated for the development of this new model, expressing concerns about the 911, Porsche's flagship model at the time, nearing its performance limits. Fuhrmann believed that expanding into grand touring cars with conventional engines could be essential for the company's future, contrasting with the unconventional sports cars like the 911. The declining sales of the 911 in the mid-1970s suggested a possible downturn in its market appeal. Fuhrmann envisioned the new range-topping grand tourer as a blend of sports coupé and luxury sedan, distinguishing it from the 911 with its more utilitarian interior and pure sports car performance. In the view to please the very important USA market, it switched to front-engined, V8 power and a more spacious interior that included two real child seats (rather than the dog seats in the 911). The goal was to create a model that could compete with offerings from Mercedes-Benz and BMW while also appealing to the American market, which was Porsche's primary market at the time.
Ordered by Ferdinand Porsche to develop a production-feasible concept for the new model, Fuhrmann commenced a design study in 1971, resulting in the creation of the 928. This model marked Porsche's first clean-sheet design for its own model. Previous Porsche models had been iterations or collaborations: the 356 bore similarities to the Volkswagen Beetle, the 911 evolved from the 356, the 914 was a joint venture aimed at replacing the Volkswagen Karmann Ghia and 912, and the 924 stemmed from a discontinued Volkswagen and Audi project.
Various drivetrain layouts were considered during early development, including rear- and mid-engine configurations, but many were dismissed due to technical and regulatory challenges. Issues with emissions and noise control, similar to those experienced with the 911, arose from cramming the engine, transmission, catalytic converter(s), and exhaust into a small rear engine bay. After determining that the mid-engine layout lacked sufficient space in the passenger compartment, Porsche opted for a front-engine, rear-wheel drive configuration.
Porsche engineers sought a large-displacement engine for the 928, and prototype units were initially equipped with a 5-liter V8 engine producing 300 PS (220 kW; 300 hp). There were discussions about utilizing a 4.6-liter 90-degree V10 engine with 88 mm bore spacing, which was a derivative of the Audi 5-cylinder engine (also used in the Lamborghini Gallardo) and based on the Volkswagen EA827 unit. However, this proposal faced objections from the Porsche board due to concerns that it might lead to rumors of a new 911 model with a front-mounted Volkswagen-based engine. Additionally, it is speculated that the board aimed to maintain some separation from the Volkswagen Group.
The resulting all-alloy M28 engine incorporated several distinctive features. Its bore spacing was 122 mm, indicating the use of thick, all-aluminum cylinder barrels without steel liners. The water jackets were notably large, hinting at the engine's potential for racing applications. To maintain a low hood line, the engine prioritized airflow, resulting in the placement of spark plugs at the top of the head. The four-bolt bearings were substantial and received oil via grooves in the block's bottom surface. They were supported by a large one-piece structure forming a lower block, with the cast aluminum oil pan bolted onto this component.
The oil and water pumps were driven by a timing belt. In 1985, DOHC engines introduced a hybrid timing system where the timing belt operated only the exhaust camshafts, while the intake camshafts were driven via an internally-mounted simplex roller chain from the exhaust camshaft. This approach simplified the timing belt layout, requiring fewer components and leading to easier and less costly maintenance. This timing system was later adopted by Porsche 944 and also by Audi and Volkswagen in their belt-driven DOHC engines.
The first two running prototypes of Porsche's M28 V8 initially utilized a single four-barrel carburetor for initial testing. However, the production cars ultimately employed the planned Bosch K-Jetronic fuel injection system. As concerns over fuel prices and availability during the 1970s oil crisis grew within the company, discussions emerged regarding the feasibility of smaller engines to improve fuel economy. There was a proposal for the development of a 3.3-litre, powerplant, suggested by Fuhrmann, but this was met with resistance from company engineers. Eventually, both sides reached a consensus on a 4.5-litre, SOHC (per bank) 16-valve V8 engine producing , in North America. This design was deemed to strike an acceptable balance between performance and fuel efficiency.
By 1973, essential development was finished and a prototype was built and under testing. At this moment, the Arab-Israeli war broke out and brought the threat of energy crisis. Sales of large and thirsty cars plunged. It was a big hit to both 928 and Porsche. The project was put into low gear and production postponed until 1977.
The finished car made its debut at the 1977 Geneva Motor Show and was subsequently released for sale later that year as a 1978 model. Despite earning early acclaim for its comfort, power, and futuristic design, sales were initially sluggish. The base prices of the 928 were considerably higher than the previous range-topping 911 model, and the shift to a front-engined, water-cooled design unsettled some traditional Porsche enthusiasts.
Following the departure of Fuhrmann, Peter Schutz, his successor, opted to continue selling both models concurrently, believing that the 911 still had a place in the company's lineup. However, legislative restrictions against rear-engined vehicles never materialized. Although the 928 didn't achieve the sales targets envisioned by Fuhrmann, it garnered a devoted following and enjoyed an 18-year production run.
Design and specifications
During its 18-year production run, the fundamentals of the 928's design remained the same, though the engine and styling underwent several changes, with a distinct ‘facelift’ separating the first generation and second generation cars.
The original 928 design was seen in both 1978 and 1979, with the body lacking both front and rear spoilers. From 1980 (1983 in North America) through 1986, front and rear spoilers were present on "S" and "S2" models, being integrated into the fastback. The first generation cars, which terminated in 1986 with the "S"/"S2" models, all featured a sharper, more angular front end with a distinct 'Shark Nose' profile. From 1987 the overall exterior design was revised and it was this shape that followed the 928 through to final production in 1995. The 1987 redesign integrated the front spoiler into the nose, smoothing out the overall nose profile to fit in with the tastes of contemporary car design & ditching the more angular, shark-nose wedge of the original cars. The rear spoiler became a separate wing rather than an integrated piece and side skirts were also added. The rear tail-light configuration was also different from previous models, with more modern light covers that brought the rear light cluster away from the inset design of the original. GTS models featured flared rear wheel arches to give more room for wider 9-inch wide wheels. Another easily noticeable visual difference between versions is the style of the wheels. Early 928s had 15-inch or 16-inch "phone dial"-style wheels, while most 1980s 928s had 16-inch slotted "flat disc" wheels, with other wheels available as an option. CSs, SEs and 1989 GTs had 16-inch "Club Sport" wheels, later GTs had 16-inch "Design 90" style wheels which were also option on same period S4s (shared with the 944 as well), the GTS used two variations of the 17-inch "CUP" wheels.
The 928 featured a front-mounted and water-cooled V8 engine driving the rear wheels. Power was transmitted according to the transaxle principle. Originally displacing 4.5 L and featuring a single overhead camshaft design, it was rated at in Europe, while smog equipment reduced the output to for cars sold in the North American market. The car would first see an increase in both displacement and output for the 1980 model year, with the introduction of the 4.7 L 928 S. The original 16v engine would continue to be developed until its final iteration in the 1985 model year with the S/S2 model, which produced a in European specification, thanks to higher compression, twin distributors with EZK ignition and Bosch LH-Jetronic fuel injection. After 1986 the 16v engine was replaced by the Porsche 32v 5.0 L V8, which Porsche used until the 928 ceased production in 1995.
In combination with the water-cooled V8 engine, Porsche utilised a transaxle in the 928 to help achieve 50/50 front/rear weight distribution. Performance of early cars were similar to the contemporary 911, despite being heavier. By the time the S/S2 specification was in production, the 928 was outperforming even the 911 Turbo in top speed tests. Early cars came with either a five-speed dog leg manual transmission, or a 3 speed Mercedes-Benz-derived automatic transmission. A four-speed automatic transmission replaced the three-speed option from 1983 in North America and 1984 in other markets. Of cars produced in 1978 and 1979, the majority were fitted with the 5 speed manual gearbox while the optional 3 speed automatic was specified less regularly. Later model years number of automatic cars was larger. 1980-95 percentage of manual cars was 34%. As so many 1978 and 1979 were with manual gearbox actual split can be 60% automatic and 40% manual.
The body, styled by Wolfgang Möbius under the guidance of Anatole Lapine used aluminium for the doors, front wing, front fenders, and bonnet to save weight, while the underlying chassis was made from galvanised steel. It had a substantial luggage area accessed via a large hatchback. Newly developed polyurethane elastic bumpers were integrated into the nose and tail and covered in body-coloured plastic; an advanced feature for the time that aided the car visually and reduced its drag. The distinctive pop-up headlamps, which remained visible in the wings even when they were retracted, completed the 928's shark-like appearance and were based on the units found on the Lamborghini Miura.