The Porsche 928 is a luxury grand tourer produced by Porsche AG of Germany from 1978 to 1995. Originally intended to replace the company's iconic 911, the 928 combined the power, poise, and handling of a sports car with the refinement, comfort, and equipment of a luxury sedan. Porsche executives believed such a flagship would have wider appeal than the compact, quirky and sometimes difficult to drive 911.
The 928 has the distinction of being the company's first production V8 powered model and the only coupé powered by a front-mounted V8 engine.
By the late 1960s Porsche had firmly established itself as a manufacturer of high-performance sports cars. Executives, including owner Ferdinand Porsche, were beginning to consider adding a luxury touring car to the line-up due to the need of a car using less fuel and being more usable in the wake of the 1970s oil crisis. Managing director Ernst Fuhrmann was pressuring Ferdinand to approve development of the new model due to concerns that the then-current flagship model, the 911, was reaching the limits of its potential. Fuhrmann believed that the future of the company relied upon grand touring cars with conventional engines rather than unconventional sports cars. Slumping sales of the 911 in the mid-1970s seemed to confirm that the model was approaching the end of its economic life cycle. Fuhrmann envisioned the new range-topping grand tourer model as being the best possible combination of a sports coupé and a luxury sedan. This would set it apart from the 911, with a relatively spartan interior and true sports car performance. The targets were that the car had to compete in par with offerings from Mercedes-Benz and BMW while also being successful in the United States, Porsche's main market at the time.
Ordered by Ferdinand Porsche to design a production-feasible concept for the new model, Fuhrmann initiated a design study in 1971, eventually yielding the 928 which was the first clean sheet design by the company for its own model; the 356 had evolved from the Volkswagen Beetle, the 911 was an evolution of the 356 and the 924 was the result of an abandoned project by Volkswagen and Audi.
Several drivetrain layouts were considered during early development, including rear and mid-engine designs, but most were dismissed because of technical and legislative difficulties. Having the engine, transmission, catalytic converter(s) and exhaust all cramped into a small rear engine bay made emission and noise control difficult which were the problems Porsche had with the 911. After deciding that the mid-engine layout did not allow enough room in the passenger compartment, a front-engine, rear-wheel drive layout was chosen. Porsche may have feared that the U.S. government would soon ban the sale of rear-engine cars in response to concern over safety problems with the rear-engine Chevrolet Corvair.
Porsche engineers wanted a large-displacement engine to power the 928, and prototype units were built with a 5-litre V8 engine rated at nearly 306 PS (225 kW; 302 hp). Ferdinand Piëch wanted this car to use a 4.6-litre 60-degree V6 engine with 88 mm bore spacing. The Porsche board objected as this move would give rise to a rumour of a new 911 with a front-mounted six cylinder engine.
The resulting all-alloy M28 engine has multiple unusual features. Its bore spacing is 122 mm, and uses thick aluminium cylinder barrels, hence the lower displacement. The engine was designed for air flow first, thus the spark plugs are located at the top of the head. The four-bolt bearings are sizeable and are fed oil via grooves in the bottom surface of the block. The oil and water pumps are driven by the timing belt, and the design of the engine allows for sufficient air flow with a low bonnet.
The first two running prototypes of Porsche's M28 V8 used one four-barrel carburetor for initial testing. The cars were sold with the planned Bosch K-Jetronic fuel injection system. When increasing concern within the company over price and availability of fuel during the oil crisis of the 1970s became an issue of contention, smaller engines were considered in the interest of fuel economy. A push began for the development of a 3.3 L 182 PS (134 kW; 180 hp) powerplant envisioned by Fuhrmann, but company engineers balked at this suggestion. Both sides finally settled on a 4.5 L, SOHC per bank 16-valve V8 rated at 240 PS (180 kW; 240 hp) (219 hp (163 kW) in North America), which they considered to have an acceptable compromise of performance and fuel economy.
The finished car debuted at the 1977 Geneva Motor Show before going on sale later that year as a 1978 model. Although it won early acclaim for its comfort, power and futuristic design, sales were slow. Base prices were much higher than that of the previous range-topping 911 model and the 928's front-engined, water-cooled design alienated many Porsche purists.
Fuhrmann's replacement, Peter Schutz, decided that the models should be sold side by side, feeling that the 911 still had potential in the company's line-up. Legislation against rear-engined vehicles did not materialize. Although it never sold in the numbers Fuhrmann envisioned, the 928 developed an avid following and had an 18-year production run.
The 928 featured a large, front-mounted and water-cooled V8 engine driving the rear wheels. Originally displacing 4.5 L and featuring a single overhead camshaft design, it was rated at 219 hp (163 kW; 222 PS) for the North American market and 240 PS (177 kW; 237 hp) in other markets. Porsche upgraded the engine from mechanical to electronic fuel injection in 1980 for US models, although power remained the same. This design marked a major change in direction for Porsche (started with the introduction of the 924 in 1976), whose cars had until then used only rear- or mid-mounted air-cooled flat engines with four or six cylinders.
Porsche utilised a transaxle in the 928 to help achieve 50/50 front/rear weight distribution, aiding the car's balance. Although it weighed more than the difficult-to-handle 911, its more neutral weight balance and higher power output gave it similar performance on the track. The 928 was regarded as the more relaxing car to drive at the time. It came with either a five-speed dog leg manual transmission, or a Mercedes-Benz-derived automatic transmission, originally with three speeds, with four-speed from 1983 in North America and 1984 in other markets. More than 80% of the cars had the automatic transmission. Exact percentage of manual gearbox cars for entire production run is not known but it is believed to be between 15 and 20%.
The body, styled by Wolfgang Möbius under guidance of Anatole Lapine, was mainly galvanized steel, but the doors, front wing, front fenders, and hood were made of aluminium in order to make the car more lightweight. It had a substantial luggage area accessed via a large hatchback. The new polyurethane elastic bumpers were integrated into the nose and tail and covered in body-coloured plastic; an unusual feature for the time that aided the car visually and reduced its drag. Another unusual feature were the pop-up headlamps which were based on the units found on the Lamborghini Miura and were integrated into the front wings.
The 928 qualified as a 2+2, having two small seats in the rear. Both rear seats could be folded down to enlarge the luggage area, and both the front and rear seats had sun visors for occupants. The rear seats are small (due to the prominent transmission hump) and have very little leg room; they are only suitable for adults on very short trips or children. The 928 was also the first vehicle in which the instrument cluster moved along with the adjustable steering wheel in order to maintain maximum instrument visibility.
The 928 included several other features such as the "Weissach Axle", a simple rear-wheel steering system that provides passive rear-wheel steering to increase stability while braking during a turn, and an unsleeved, silicon alloy engine block made of aluminium, which reduced weight and provided a highly durable cylinder bore.
Porsche's design and development efforts paid off during the 1978 European Car of the Year, where the 928 won ahead of the BMW 7 Series, and the Ford Granada. The 928 is the only sports car so far to have won this competition, where the usual winners are mainstream hatchbacks and sedans/saloons from major European manufacturers. This is regarded as proof of how advanced the 928 was, compared to its contemporaries.
Styling was the same 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" models, rear spoilers being integrated into the hatch. From 1987 through 1995, the front spoiler was integrated into the nose and the rear spoiler became a separated wing rather than an integrated piece, and side skirts were added. The rear tail-light configuration was also different from previous models. GTS models had wider rear fenders added to give more room for 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, 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.
Porsche introduced a refreshed 928 S into the European market in 1980 model year, although it was summer of 1982 and MY 1983 before the model reached North America. Externally, the S wore new front and rear spoilers and sported wider wheels and tires than the older variant, but the main change for the 928 S was under the hood, where a revised 4.7 L engine was used. European versions debuted with 221 kW; 296 hp (300 PS), and were upgraded to 228 kW; 306 hp (310 PS) for the 1984 model year. From 1984 to 1986, the S model was called S2 in United Kingdom. These cars used Bosch LH-Jetronic fuel injection system and purely electronic Bosch ignition, the same systems used on the later 32-valve cars, though without the pollution controls. North American-spec 1983 and 1984 S models used among other differences, smaller valves, milder camshafts, smaller diameter intake manifolds, and additional pollution equipment in order to meet emissions regulations, and were limited to 174 kW; 237 PS (234 hp) as a result. Due to low grade fuel, the 16-valve low compression S engine was made for Australian market in the 1985 model year. It had a 9.3:1 compression ratio pistons as opposed to the normal 10.4:1 but used the same large intake, high lift cams, large valves etc. of other S engines.
As the faster European model was not available in the United States and Canada during the first three years of its existence, a "Competition Group" option was created to allow North American customers to have an S model lookalike with front and rear spoilers, 16-inch flat disc wheels, sport seats, sport springs and Bilstein Shock Absorbers. Customers could specify paint and interior colours the same way as on a normal 928. Two cars were made in the late 1980 model year for U.S. with this option. The package was officially available in 1981 and 1982 model years and was canceled in 1983 when the S model became available for these markets. Many cars have had S model features added by subsequent owners, making original "Competition Group" cars difficult to distinguish without checking option codes.
In the 1982 model year, two special models were available for different markets. 202 "Weissach Edition" cars were sold in North America. Unusual features were champagne gold metallic paint, matching brushed gold flat disc wheels, two-tone leather interior, a plaque containing the production number on the dash and the extremely collectible three-piece Porsche luggage set. It's believed these cars were not made with S spoilers even though these were available in U.S. during this time period as part of the "Competition Group" option. The "Weissach Edition" option was also available for the US market 911 for the 1980 model year and 924 for the 1981 model year.
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