Porsche 928, The Complete Buying Guide

Overview

The Porsche 928 is one of the great misunderstood cars in automotive history. Launched in 1977 as a front-engined, water-cooled V8 grand tourer, it was designed to replace the 911. It never did. The 911 loyalists refused to let their air-cooled icon die, and the 928 spent its entire 18-year production run living in the shadow of the car it was supposed to succeed. That rejection is your opportunity, because the 928 is a genuinely brilliant car that remains undervalued relative to its engineering, its performance, and its place in Porsche history.

The 928 was radical for Porsche. A front-mounted all-aluminium V8, rear transaxle for perfect weight distribution, the innovative Weissach rear axle that provided passive rear-steer for stability under braking, and a level of luxury and refinement that no 911 could match. It won European Car of the Year in 1978, the only sports car ever to receive that award. Over 18 years of production, the V8 grew from 4.5 litres and 240 horsepower to 5.4 litres and 350 horsepower in the final GTS, and the car evolved from a comfortable GT cruiser into a genuine autobahn stormer.

Today, the 928 is attracting serious attention. Values have been climbing steadily as enthusiasts recognise what it always was: a beautifully engineered, continent-crossing grand tourer with a glorious V8 soundtrack. But these are complex cars with expensive problems if neglected. Buying well is everything.

Which Variant to Buy

928 (1977-1982)

The original 928, powered by the M28/01 4.5-litre SOHC V8 producing 240 horsepower. A single overhead cam per bank, Bosch K-Jetronic fuel injection, and a relatively simple engine management system. Available with a 5-speed manual or 3-speed automatic. The early cars have pop-up headlights and the cleanest, most elegant body design, free of the later models’ aero additions.

The original 928 is the most affordable entry point and mechanically the simplest. The SOHC engine is robust and easier to work on than the later DOHC units. However, any surviving car is now over 40 years old, and finding one that hasn’t been neglected or bodged is increasingly difficult. These are not the performance bargain that the later cars are, they’re for purists who appreciate the original design intent.

928 S (1980-1986)

The first significant evolution. The engine grew to 4.7 litres (M28/07 through M28/10, depending on market and year) and gained double overhead cams with four valves per cylinder, producing 310 horsepower in European specification. The S received larger brakes, wider tyres, revised suspension, and the distinctive front spoiler and rear bumper treatment.

The S is a significant step up in performance from the base 928, and the DOHC engine sounds magnificent at full chat. European-spec cars are the ones to look for, North American cars were detuned with lower compression and catalytic converters. Parts availability is good, and the S represents solid value. Watch for early DOHC timing belt issues, this is where the interference engine concern becomes critical.

928 S4 (1987-1991)

The S4 is where the 928 hits its stride. The engine is now 5.0 litres (M28/41-42), producing 320 horsepower. Bosch LH-Jetronic fuel injection replaced the earlier K-Jetronic, the body received smoothed bumpers, a revised nose with integrated fog lights, and the interior was significantly improved. The S4 is noticeably faster, more refined, and more modern-feeling than the earlier cars.

The S4 is the sweet spot for many buyers. It has the performance to feel genuinely fast by modern standards, the refinement to cover long distances in comfort, and it’s significantly cheaper than the GTS. Most S4s are automatics, the 4-speed unit is smooth but not exciting. A manual S4 is rare and commands a meaningful premium.

928 GT (1989-1991)

The GT is essentially a sportier S4. The same 5.0-litre engine is tuned to 330 horsepower with revised camshafts and engine management. Stiffer suspension, the manual gearbox as standard (in most markets), and sportier interior trim. The GT was only available as a manual in most configurations, making it the driver’s choice.

Production numbers were relatively low, making the GT rarer than the S4 or GTS. It occupies an interesting middle ground: more sporting than the S4, less expensive than the GTS, and with the manual gearbox as standard. If you want a 928 to drive hard, the GT is worth seeking out.

928 GTS (1992-1995)

The GTS is the holy grail. The final evolution of the 928, with a 5.4-litre V8 (M28/49-50) producing 350 horsepower and 369 lb-ft of torque. The body was revised with wider rear haunches (adding 30mm to the rear track), a more integrated rear end, and cup mirrors. The suspension was revised, the brakes were upgraded, and the interior received the best materials Porsche could source.

The GTS is a seriously fast car, 0-100 km/h in 5.2 seconds, and it handles with a precision that belies its 1,620 kg kerb weight. It was available with both manual and automatic transmissions, and the manual GTS is the rarest, most desirable 928 of all. Approximately 2,831 GTS models were built in total, with manual cars being a small fraction of that.

Buy recommendation: For a first 928, the S4 automatic is the sensible entry point. It’s affordable, it’s refined, it’s fast enough to be exciting, and parts and specialist knowledge are readily available. If you want the ultimate 928 experience and budget permits, a GTS manual is the pinnacle, one of the great front-engined GTs ever built.

What to Look For

Engine

The 928’s all-aluminium V8 is a durable engine when maintained, but neglect is catastrophic. These are interference engines, and the timing belt system is the single most critical inspection item.

Timing Belt (All DOHC models, 1980 onwards): This is non-negotiable. The 928’s V8 has a complex dual-cam timing belt setup driving four camshafts. If the belt breaks, valves hit pistons and the engine is destroyed. The belt must be replaced every 4-5 years or 60,000 km, along with the tensioner rollers and water pump (which is driven by the timing belt). Demand documented proof of the last belt change. If there’s no documentation, budget $3,000-5,000 AUD for immediate replacement and negotiate the purchase price accordingly. This is not something you defer.

Oil Leaks: Check the cam covers, the oil cooler lines (which run under the car and corrode), and the rear main seal. A light weep from the cam covers is normal on any 928 with age. Active dripping from the oil cooler lines or rear main seal indicates deferred maintenance. Rear main seal replacement requires removing the torque tube, a $3,000-5,000 job.

Coolant System: Inspect the coolant for cleanliness (should be green or pink, not brown). The 928’s underbody coolant pipes are steel and corrode from the outside in. Replacing them is a significant job because they run the length of the car. Check for any evidence of overheating (warped head gaskets, staining around the radiator neck). The water pump is driven by the timing belt and should be replaced with each belt change.

Start-up and Running: Listen for any rattling or ticking on cold start. The hydraulic lifters should quiet down within 30 seconds. Excessive ticking beyond that suggests worn lifters or low oil pressure. Rev the engine and watch for smoke from the exhaust, blue smoke indicates oil burning from worn valve guides or rings.

Transmission and Torque Tube

Automatic Transmission: Most 928s are automatics. The 3-speed (early cars) and 4-speed (S4 onwards) units are Mercedes-sourced and generally reliable. Check for smooth shifts, no slipping, and no harsh engagement. Fluid should be clean and red, not brown or burnt-smelling.

Manual Transmission: The 5-speed manual is a relatively rare find. Check for smooth engagement in all gears, no grinding or crunching, and no excessive play in the shift linkage. The synchros on second gear tend to wear first.

Torque Tube: The torque tube connects the front engine to the rear transaxle and contains the propeller shaft. The torque tube bearing (centre bearing) wears and produces a vibration or rumble at certain speeds, typically around 80-120 km/h. Replacement is a significant job requiring separation of the engine from the transaxle. Budget $3,000-5,000 AUD.

Electrical and Electronics

The 928 is a complex car electrically, particularly the 1987-onwards models with the Bosch LH-Jetronic fuel injection and extensive electronic systems.

LH Fuel Injection Module (1987+): The Bosch LH-Jetronic electronic control unit is mounted in the engine bay and suffers from heat-related failure. Symptoms include rough idle, poor cold starting, hesitation under acceleration, and eventually a no-start condition. A rebuilt module costs $800-1,500 AUD. This is a known weak point and a common repair item.

Wiring Harness: The 928’s wiring harness deteriorates with age, particularly in the engine bay where heat breaks down the insulation. Look for brittle or cracked wiring, corroded connectors, and any evidence of electrical tape repairs (which indicate previous problems). A full harness replacement or refurbishment is $3,000-8,000.

Power Windows and Central Locking: The window regulators are a common failure point. Test every window, including the sunroof if fitted. Slow or non-functional windows are typical and the parts are available, but it’s a negotiation point. Central locking failures are also common.

Suspension and Brakes

Weissach Rear Axle: The innovative Weissach axle provides passive rear-steer for stability. The bushings in this system wear, causing vague handling and a tendency for the rear to feel unsettled. Worn Weissach bushings are very common on high-mileage cars. Replacement is $1,500-3,000 at a specialist.

PSD (Porsche Slip Differential): The later cars (S4 onwards) have a viscous limited-slip differential. The PSD unit can lock up or fail, causing the rear end to feel unstable or producing a binding sensation in tight turns. A replacement or rebuilt unit is $2,000-4,000.

Brakes: Check for even braking, no pulling to one side, and no vibration through the pedal (which indicates warped rotors). The brake calipers on the later cars are large and effective. Check the brake lines for corrosion, particularly the hard lines that run under the car.

Body and Interior

Rust: The 928’s body is steel with aluminium doors, bonnet, and front guards. The steel sections can rust, particularly around the rear wheel arches, the windscreen surround, the door sills, and the underbody. Australian cars tend to fare better than European examples, but check carefully underneath for any corrosion on the floor pan or structural members.

Dashboard: The 928 suffers from the same dashboard cracking issue as the 944. UV exposure causes the dashboard to crack extensively, and a cracked dash is expensive to repair or replace ($2,000-5,000 for a recovered or replacement dash). Check the condition of the dashboard carefully, it’s often the most visually obvious issue in the cabin.

Headlights: The pop-up headlights (all models up to the S4) should rise and fall smoothly. The motors fail and replacement is $500-1,000 per side. The S4 and later have flush-mounted headlights which are simpler.

Price Guide (2026 AUD)

928 (1977-1982)

Condition	Price Range
Project / rough runner	$12,000-$20,000
Driver condition, needs work	$20,000-$30,000
Good condition, maintained	$30,000-$40,000

928 S (1980-1986)

Condition	Price Range
Project / rough runner	$15,000-$25,000
Driver condition, needs work	$25,000-$35,000
Good condition, maintained	$35,000-$50,000

928 S4 (1987-1991)

Condition	Price Range
Rough / needs recommissioning	$20,000-$30,000
Driver condition, auto	$35,000-$55,000
Good condition, auto	$55,000-$70,000
Good condition, manual	$70,000-$90,000

928 GT (1989-1991)

Condition	Price Range
Driver condition	$55,000-$75,000
Good condition, manual	$75,000-$100,000
Excellent / low km	$100,000-$130,000

928 GTS (1992-1995)

Condition	Price Range
Driver condition, auto	$70,000-$90,000
Good condition, auto	$90,000-$120,000
Good condition, manual	$120,000-$160,000
Excellent manual / low km	$160,000-$200,000+

Manual transmission cars command a 30-50% premium over equivalent automatics across all variants. The GTS manual is the undisputed king of 928 values and continues to appreciate.

Running Costs

The 928 is not a cheap car to own. It is a complex, front-engined V8 Porsche with expensive parts and labour-intensive service requirements. Go in with your eyes open.

Annual servicing: A standard annual service (oil, filters, fluids check, inspection) at a Porsche specialist runs $800-1,200 AUD. Budget $2,500-4,000 for a major service including timing belt, water pump, rollers, and coolant flush (every 4-5 years).

Fuel: The 928 drinks. Expect 14-18 L/100km in mixed driving, 20+ L/100km if you’re enjoying yourself. The 86-litre tank needs 98 RON premium, so a fill-up is around $200 AUD. Plan for $150-250/month in fuel depending on usage.

Tyres: The later cars run staggered tyre setups (wider rears). A set of quality tyres costs $1,200-2,000 AUD. Expect to replace them every 20,000-30,000 km depending on driving style.

Insurance: Agreed-value classic car insurance is the way to go. Expect $1,000-2,500/year depending on the car’s agreed value, your age, and usage pattern. The GTS will cost more to insure than an S4.

The big-ticket items: The timing belt service ($3,000-5,000 every 5 years), clutch replacement on manual cars ($4,000-7,000, requires torque tube separation), torque tube bearing ($3,000-5,000), and any engine work (valve adjustment, head gasket, etc.) are the costs that catch people out. Budget a $5,000 annual contingency fund on top of routine maintenance, especially in the first two years of ownership while you discover and address deferred maintenance.

Final Advice

The 928 is a car that rewards careful buying more than almost any other classic Porsche. A well-maintained example with documented history is a joy: a smooth, powerful, long-legged GT that does things no 911 can. A neglected example is a money pit that will punish you with four-figure repair bills month after month.

Buy the best car you can afford, not the cheapest. A $55,000 S4 with a folder of receipts and a recent timing belt service is a vastly better purchase than a $25,000 S4 with no history and a mystery maintenance past. The difference in purchase price will be consumed by the neglected car’s repair bills within the first year.

Find a specialist. The 928 is not a car for a general mechanic, and it’s not well served by many mainstream Porsche workshops either. Find a 928 specialist or a Porsche independent with specific 928 experience. The Porsche 928 Australia community is small but knowledgeable and welcoming, join before you buy and ask for recommendations.

Pre-purchase inspection is mandatory. Budget $500-800 for a thorough inspection by a 928 specialist, including compression test, timing belt inspection, suspension assessment, and electronic system check. This is the best money you will spend in the entire purchase process.

And finally, drive one before you buy. The 928 is a very different car to a 911. It’s a grand tourer, not a sports car. It’s about covering distance in speed and comfort, with a V8 rumble that no flat-six can replicate. If that’s what you want, the 928 is magnificent. If you want a weekend canyon carver, the 911 or 944 might be a better fit. Know what you’re buying and buy it for the right reasons.