Buyers Guide

By Bruce Anderson

928

1978 928

1985 928S

1990 928 GT

1992 928 GTS

In the eyes of most 928 enthusiasts, Porsche’s big V8 coupe is the best grand touring car ever made. The problem was that the 928 was never a best-seller. Only 57,998 were built in 19 years of production, with 25,105 of them sold in the United States. The single-year production peak was in 1979, when Porsche manufactured 5,438 928 models. Single-year production exceeded 5,000 units only once more, in 1984.

The 928 was an expensive car in its day — which was an obvious factor in its less-than-spectacular sales figures. But the bigger problem was that it never caught on with large numbers of traditional Porsche buyers. Today, the 928 has a steep depreciation curve, so it can be a good buy as a used car. That said, potential buyers should remember that the 928 was not only expensive when new, but also expensive to maintain and fix.

In many ways, the 928 is still a relatively contemporary GT car and reasonable prices make it an attractive choice on the used Porsche market. If you are looking for a used Porsche, I recommend that you test drive a 928. It is an extremely enjoyable car to drive, particularly at high speeds. But even on tight, twisty roads, it tends to come alive and “shrink around the driver.” Best of all, early versions of the 928 often sell for less than 25 percent of their original price. The very earliest 928s and the GTSs tend to be more sought-after, but it’s clear that the values for all 928s have taken a hit in this sour economy.

When the 928 was conceived, the goal was to build a modern car based on more conventional parameters than the 911, but with the potential to exceed the 911’s performance. There was no question the 928 did achieve high levels of performance — when first introduced, the 928 had an all-aluminum, 4.5-liter V8 engine that produced a very respectable 230 hp in the U.S. version, while the European version produced 240 hp. All early examples were fitted with Bosch CIS fuel injection.

The earliest 928s have some undesirable features and I encourage you to avoid them. The 1978 and 1979 models had problems with their electrical systems, vacuum door locks, and air-conditioning. Changes made for model-year 1980 fixed these problems and made the 928 much more reliable, so I recommend looking for 1980-and-newer cars. Also revised for the 1980 U.S. model was the fuel injection, camshaft profile, and compression ratio. These changes helped make the engine more flexible and more emissions-friendly.

Among earlier 928s, some cars are more desirable than others. The 928 initially came with a five-speed manual transmission or a three-speed automatic that Mercedes-Benz built for Porsche. I used to recommend the automatic because the manual transmission had several problems. The clutch used in the early 928s (up until 1987) was a multiple-disc unit and was prone to clutch chatter if abused at all. Also, the early five-speed transmissions used Porsche-designed synchronizers and were prone to premature failures. The transmission was changed to one that utilized Borg-Warner synchronizers in 1985. These newer transmissions shift better and are more durable than the earlier units.

Despite my preference for the automatic transmission in the early 928s, the three-speed automatic wasn’t much fun. I would rather look for a car with the later four-speed automatic transmission. The U.S. and Japanese markets received the four-speed automatic in 1983, while other markets had to wait until 1984. I have always felt that the automatic transmission fits the character of the 928 as a luxury GT better than the five-speed manual transmission does.

I must admit that my attitude has been strongly influenced by problems with the early manual transmissions and the multiple-disc clutch used up until 1987. If you are in the market for a 928 and want a manual, I recommend looking at 1987-and-newer cars if they are within your price range. However, the multiple-disc clutches can be easily replaced in any of the earlier five-speed cars, though it is an expensive upgrade. I could probably live with the early Porsche synchro gearbox more easily than with the early clutch.

For model-year 1980, the European market got the first version of the 928S with increased displacement, more power, larger brakes, spoilers, improved suspension, and new forged Fuchs alloy wheels. The displacement was up to 4.7 liters (4664 cc), the compression was up to 10:1, and the power was up to 300 hp. Top speed was 155 mph and the 928S accelerated from 0–100 mph in 14.6 seconds.

In 1981, Porsche offered what they called a competition package for the U.S. market that upgraded the suspension and used the wheels and spoilers of the European 928S. But the larger 4.7-liter engine was not available in the U.S. until 1983. Even then, the power only went up to 234 hp. The U.S. and Japanese cars received the four-speed automatic transmission in 1983 while Rest of World models got the four-speed automatic transmission in 1984.

The motor mounts were changed on 1983 models to hydraulic mounts similar to those used on the 944, which helped to block low-frequency vibrations. The belt tensioner was also changed for 1983 to a system that used hydraulic damping. The U.S. 928 remained nearly unchanged through 1984. The European 928S was upgraded again in 1984 with L-Jetronic fuel injection that incorporated a hot wire air-flow sensor. Power output was rated at 310 hp, but reputed to be more like 330 hp.

The U.S. 928 changed considerably for 1985 with the introduction of a new, larger engine. This new engine, code named VW 4C 32V was equipped with two overhead camshafts for each bank of cylinders, four valves per cylinder, LH fuel injection with hot wire air-flow sensor, and an EZF ignition system. The new engine produced 288 horsepower at 5750 rpm, which was a big increase over the 234 horsepower that the U.S. cars had before. Torque was up to 302 ft/lbs at 2700 rpm. The manual transmissions were also new for 1985, using superior Borg Warner synchronizers.

For the 1986 model year, the 928 was largely unchanged, though bigger brakes with Brembo four-piston calipers were added to 1986 928s from serial number 1000 on. Also, the 1986 928 had anti-lock brakes as standard equipment worldwide. The radio antenna was in the windshield.

In 1987, the 928 S4 was introduced with a single engine for the world market. The 4 in the model designation stood for the fourth series of development and not for the four-valves-per-cylinder heads, as many people think. The 928 S4 had an improved induction system with tuned resonance charging that provided a broad power curve and 320 DIN horsepower at 6000 rpm, with peak torque checking in at 317 ft/lbs at 3000 rpm. To reduce the temperature in the pistons, oil spray jets were installed in the crankcase to spray oil on the bottom of the piston crowns. A knock sensor was incorporated in the ignition system to permit more flexibility in the engine’s fuel requirements.

The 928 S4 also introduced new bodywork with different bumper designs and spoilers front and rear that greatly improved aerodynamics. The 928 S4 introduced a larger diameter, single-disc clutch for smoother clutch operation. The front brake calipers had their piston sizes changed to reduce uneven brake pad wear. Top speed was up to 165 mph, while 0–60 took 5.7 seconds and the quarter-mile passed in 14.1 seconds.

In the spring of 1987, the automatic transmission shift program was changed to start out in second gear and roll to a stop in second gear under certain operating conditions. If the driver starts off with a heavy throttle input, the transmission downshifts to first gear. For 1988, the rear spoiler’s folding mechanism was omitted worldwide. The front brakes were changed to incorporate curved cooling ribs. The ABS control unit and software were changed, as well.

In 1989, the automatic transmission’s shift program was revised again to permit sportier driving. The program revision changed the rpm limit for upshifts when the accelerator was floored. All 1989 928s were equipped with asbestos-free brake pads and brake-pad-wear indicators.

For 1990, the five-speed version of the 928 was called the 928 GT. Power for the GT was increased to 330 hp, or 10 hp more than the automatic. The 928 GT gained extra power with more aggressive camshafts. The 928 GT also had a lightweight, twin-pipe exhaust system with two tailpipes. The 928 GT had a short-ratio manual transmission connected to a multi-plate, limited-slip differential. Also for 1990, all 928 models were equipped with the electronically-controlled Porsche limited-slip differential (PSD). The twin-pipe final muffler was standard on both 928 models. A shorter final drive was selected for the five-speed transmission to optimize acceleration and a tire-pressure control system was adopted.

For 1991, electronically-controlled cooling flaps that had been on the 928 since 1987 were deleted. Otherwise, only subtle refinements like a different shift lever, lighter power steering pump with raised operating pressures, crank damper, and improved door seals were added.

In the spring of 1992, the 928 GTS was introduced. In the U.S., the GTS was considered a 1993 model. The displacement was increased to 5.4 liters (5397 cc) and power was increased to 350 hp. The clutch had increased contact pressure to cope with the increased power. The manual transmission was reinforced and had a front-mounted transmission oil cooler. The automatic transmission had a revised shift program adapted to the new engine’s power curve. More aerodynamic outside mirrors, larger rear fender flares, and five-spoke, 17-inch wheels were added.

The front brake rotors were increased in diameter to 322 mm. The Brembo brake calipers were different and the surface area of the brake pads was increased. The tire pressure monitoring system was deleted for the 1994 model. A particle filter was also added to the climate-control system to filter dust and pollen out of the passenger compartment. The 928 GTS was virtually unchanged for 1995, which was its last year of production. Not many 928 GTS models were built for the U.S. over four years: 192 of the 1992 car, 100 of the 1993 car, 100 of the 1994 car, and only 90 of the final 1995 car.

Which 928 to Buy?

Generally speaking, 928s are reliable cars. Most of their problems are related to accessories rather than basic mechanicals. The original, two-valve-per-cylinder V8 is particularly robust. The later four-valve V8 is, too — so long as it has been maintained properly. The cam-drive belts are critical maintenance items in the four-valve cars as well as the two-valve Euro cars. If a belt fails, it can cause expensive damage to the valve gear and possibly to the engine internals. Be sure that any 928 you’re considering has had regular belt maintenance every 30–45,000 miles, which should be the regular replacement interval. In addition, it is important to inspect belt condition every time the car is serviced.

I usually recommend buying the latest Porsche you can afford, and this advice applies to 928s as well. Check the maintenance history of any used 928 carefully, and be sure to have a pre-purchase inspection performed. The 1987-and-newer models are my favorites, while the 928 GTS is the ultimate 928. Unfortunately, these last and most desirable models are scarce and usually expensive. The rest of the 928s continue to be reasonably-priced grand touring cars with an enthusiastic following. In their day, these Porsches were probably the best grand-touring cars you could buy.

Today, the 928 is still a wonderful car and a lot of fun to drive. It can also be a good value on the used car market. Just remember that it is a complex car and that it can be expensive to maintain and repair. A rough 928 can rack up expenses that exceed the cost of buying a nicer example in the first place. With careful inspection, however, a used 928 can be an exceedingly pleasurable car to own.

How to Use Our Numbers

High vs. Low: Our estimates reflect values for the majority of cars on the market. On the High end you should find cars with no more than 7,000 to 9,000 miles per year, excellent paint, normal wear but little tear, and no glaring mechanical or cosmetic issues. On the Low end you should find complete, running cars with higher mileage, cosmetic damage, and/or minor mechanical needs. Generally speaking, we allow an additional 10 percent for mileage lower than 7,000-9,000 miles per year, and subtract 10-25 percent for past body damage that required paintwork. Due to the high cost to repair and restore Porsches, cars at the High price point often represent better long-term value than those at the Low end, as the cost to make a rough car nice will exceed the difference between the two.

Exceptions: Of course, some cars fall outside of our range — on both ends. Cars with major needs (excessive rust, blown engines, crash damage, etc.) and cars with salvage titles are typically worth less, often a lot less. On the other side, older or desirable Porsches with very low miles and original cosmetics in immaculate condition, cars benefitting from top-end restorations, and cars with interesting histories can command far higher prices, sometimes doubling or tripling our High estimate. An immaculate, totally original 1972 911E with 143,000 miles might qualify, since 140,000 to 180,000 miles would be considered normal in a 20-year-old 911. If the same car had 43,000, 4,300, or 430 miles, we'd expect the price to go up exponentially — but such cars are truly exceptional examples, and their prices are often truly exceptional, too. When dealing with such cars, seek the advice of an expert or get an independent appraisal.

Where These Numbers Come From

Our value estimates are assembled by Excellence Technical Editor, PCA appraiser, and noted Porsche expert Bruce Anderson. He looks to established price indexes such as Kelly Blue Book (KBB), National Automobile Dealer Association(NADA) Used Car Guide, Cars of Particular Interest (CPI) Price Guide, as well as other references. Auction results are considered, as well, as are Excellence Reader Sales Reports, which carry comprehensive descriptions and real private-party transaction prices. Still, says Anderson, auction prices and reader reports must be approached with caution: "While I do get a lot of feedback from readers, there is no way that I get enough to base my values on anymore than value books get enough auction data to totally base the market values on. We all do a lot of interpolation to fill in the gaps.

"I get sales information anywhere that I can and I look at what everyone else is doing, then plot my own numbers after much interpolation and head scratching," continues Anderson. "I use our Reader Sales Reports as one of my sanity checks to see if I'm really heading in the correct direction. I also consider asking prices as a trend indicator. If, all of a sudden, we see asking prices go up or down, it's a good indication that something is happening with the market. But you need a lot of data to really know where things are going. When the market is volatile, as it is now for 356s and early 911s, it is hard to track the prices without predicting them. Sometimes, I think the prices look high (1974-1989 911s, for instance), while others look too low (some 993s and early 911s). Most of the time, though, they seem pretty close to the mark given that we're talking about limited numbers of sales to deal with, price guides that are all over the place, and the need to peg a national market with hot and cold spots."