Porsche 928

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 Porsche executives believed that the 928 would have broader appeal compared to the compact, somewhat outdated, and slow-selling air-cooled 911.

It achieved high top speeds, and earned recognition upon its 1978 release by winning the European Car of the Year award.

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.