The evolution of the 928 during its 18 years of production is quite subtle, and often confuses individuals interested in purchasing a 928. The tables below show the major differences, which were largely made to the nose, tail, interior, engine and rims.

Information detailing the evolution through the model years

1978
• Model designation: 928
• Engine displacement: 4.5 L
• Valves: 16
• Bosch K-Jetronic injection
• Power: 219 hp (163 kW) North America / 240 PS (177 kW) ROW
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1979
• Model designation: 928
• Engine displacement: 4.5 L
• Valves: 16
• Bosch K-Jetronic injection
• Power: 219 hp (163 kW) North America / 240 PS (177 kW) ROW
• Changes:
o Battery box integrated as part of the body, was previously mounted to gearbox. Gearbox shocks deleted.
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1980
• Model designation: 928 North America/928 and 928 S ROW
• Engine displacement: 4.5 L/4.7 L (S)
• Valves: 16
• Power: 229 hp (167 kW) North America / 240 PS (177 kW) (4.5) and 300 PS (221 kW) (4.7 S) ROW
• Changes:
o Bosch L-Jetronic injection to North America.
o Front & rear spoilers on S model.
o Manual gearbox changed during model year requiring shorter torque tube also.
o "S" brakes into use during model year in all ROW cars.
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1981
• Model designation: 928 North America/928 and 928 S ROW
• Engine displacement: 4.5 L/4.7 L (S)
• Valves: 16
• Power: 229 hp (167 kW) North America / 240 PS (177 kW) (4.5) and 300 PS (221 kW) (4.7 S) ROW
• Changes:
o "Competition Group" option available in US.
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1982
• Model designation: 928 North America/928 and 928 S ROW
• Engine displacement: 4.5 L/4.7 L (S)
• Valves: 16
• Power: 229 hp (167 kW) North America / 240 PS (177 kW) (4.5) and 300 PS (221 kW) (4.7 S) ROW
• Changes:
o Vibration damper added into torque tube between 2nd and 3rd support bearing on manual gearbox cars and behind 2nd bearing on automatics. Reverse gear lock added to manual gearbox.
o "S" brakes into use in US models.
o 205 "Weissach Edition" made for US market.
o 140 "50th Jubilee" 928 S made for ROW markets.
o 4.5 L ROW model and US "Competition Group" option dropped from production at end of 1982 model year.
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1983
• Model designation: 928 S
• Weight: 3300 lb/1500 kg
• Engine displacement: 4.7 L
• Valves: 16
• Power: 239 hp (174 kW) @ 5200 rpm North America / 300 PS (221 kW) ROW
• Changes:
o New style hydraulic motor mounts. Engine shocks deleted at same time.
o 4-speed automatic transmission for North America. Cars body and torque tube changed to accommodate longer gearbox.
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1984
• Model designation: 928 S/928 S2 UK
• Weight: 3300 lb/1500 kg
• Engine displacement: 4.7 L
• Valves: 16
• Power: 239 hp (174 kW) @ 5200 rpm North America / 310 PS (228 kW) ROW
• Changes:
o S model renamed S2 in UK market.
o Bosch LH-Jetronic injection and 4-speed automatic transmission added to the ROW model. Torque tube shortened like on US model in previous year.
o EZF ignition system using dual distributors makes debut on ROW cars. This allows higher 10.4:1 compression and increased torque. Compression change done in middle of model year once 10.0:1 compression ratio resulting piston stock were used up in production.
o ABS brakes optional for the first time in Porsche.
o At 146 mph (235 km/h) US model top speed, Porsche boldly claims the 928 S to be "the fastest street legal production car sold in the US".
o Important safety related change to front suspension lower ball joints on all cars in September 1983.
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1985
• Model designation: 928 S/928 S2 UK
• Weight: 3300 lb/1500 kg
• Engine displacement: 5.0 L North America/4.7 L ROW
• Valves: 32 North America/16 ROW
• Power: 288 hp/292 PS (215 kW) North America / 310 PS/306 hp (228 kW) ROW / 275 PS/272 hp (202 kW) (4.7) Sweden and Switzerland
• Changes:
o New 5.0 liter 32-valve LH-Jetronic injection and EZF ignition 288 hp engine for US market. Top speed is now in excess of 155 mph (250 km/h) for US models also.
o Lower compression (9.3:1 vs 10.4:1 for normal ROW version) 16-valve engine for Sweden and Switzerland. Compression change was done with different shape piston tops. Only together with automatic transmission. Engine number is same M28/22 as in high compression 16V engines. Only outside indication for different pistons is option code M151.
o LH-Jetronic control box design changed in ROW cars.
o New style front seats. Redesigned more modern looking door panels when multi speaker stereo was ordered. Gearbox synchromesh changed to Borg Warner design and shorter gear lever, improving driveability on manual transmission cars. Shims left out from front end of torque tube drive plate in automatic cars, this sometimes cause engine thrust bearing failures.
o Radio antenna moved to imbedded windshield wire.
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1986
• Model designation: 928 S/928 S2 UK
• Weight: 3300 lb/1500 kg
• Engine displacement: 5.0 L North America/4.7 or 5.0 L ROW
• Valves: 32 North America/16 or 32 ROW
• Power: 288 hp/292 PS (215 kW) North America / 310 PS/306 hp (231 kW) (4.7) or 288 PS/284 hp (215 kW) (5.0) ROW / 275 PS/272 hp (202 kW) (4.7) Sweden and Switzerland
• Changes:
o Lower compression (9.3:1 vs 10.0:1 for US version) 32-valve engine optional for some ROW markets with catalytic converter, standard in Australia. Compression change was done with different shape piston tops.
o Lower compression (9.3:1 vs 10.4:1 for normal ROW version) 16-valve engine for Sweden and Switzerland. Compression change was done with different shape piston tops. Only together with automatic transmission. Engine number is same M28/22 as in high compression 16V engines. Only outside indication for different pistons is option code M151.
o So called "S4" suspension and brakes in all 1986 ROW cars, from VIN 1001 and November 1985 forward in North America. No US models made with VIN ending between 0938 and 1000 due to parts change.
o ABS brakes became standard for all markets during model year production.
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1987
• Model designation: 928 S4
• Weight: 3500 lb/1590 kg
• Engine displacement: 5.0 L
• Valves: 32
• Power: 316 hp/320 PS (236 kW) ROW and North America / 300 PS/296 hp (221 kW) Australia
• Changes:
o New style front & rear bumpers and rear wing spoiler. Redesigned front and rear bumper light assemblies. Body changed compared to earlier models to accommodate larger rear lamps, rear sears area modified to give room for new torque converter.
o Different style pistons, cylinder heads, camshafts, intake and larger intake valves compared to earlier 5.0 L engines. Nominal compression ratio 10.0:1, true ratio between 9.4:1 and 10.0:1 depending on parts used. Cylinder head studs used in all earlier engines replaces with bolts making it easier to remove heads while engine is in engine bay.
o Updated LH-Jetronic injection and ignition changed to EZK system, two knock sensors added to engine. Single disk clutch on manual transmission cars, larger torque converter on automatics.
o Upwards folding rear spoiler and piston oil squirters in engine block on early cars only.
o Different horsepower rating for Australia due to different ignition map used because of possible low grade fuel.
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1988
• Model designation: 928 S4 and 928 CS North America/928 S4 and 928 CS ROW/928 S4 and 928 SE UK
• Engine displacement: 5.0 L
• Valves: 32
• Power: 316 hp/320 PS (236 kW) (S4, CS and SE) ROW and North America / 300 PS/296 hp (221 kW) (S4) Australia
• Changes:
o Lighter 928 CS (Club Sport) version available in Continental Europe and US, 928 SE (S4 Sport) in UK. Only model year for US CS and UK SE. ROW CS use different VIN sequence than normal ROW S4.
o Stronger torque tube with 3mm thicker center shaft for automatics.
o Pistons with strengthened skirt into use in February 1988. Oil drainage improved in piston skirts.
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1989
• Model designation: 928 S4 and 928 GT North America/928 S4, CS and GT ROW/ 928 S4 and GT UK
• Engine displacement: 5.0 L
• Valves: 32
• Power: 316 hp/320 PS (236 kW) (S4) / 326 hp/330 PS (243 kW) (GT)
• Changes:
o Digital trip computer/warning system added to dashboard, ignition circuit monitor system added.
o For Australian cars same ignition maps resulting same horsepower rating as in other markets.
o Shorter final drive on North American manual transmission S4, same ratio as used in ROW 5-speed cars to simplify production.
o RDK tyre pressure monitoring system optional on ROW S4, standard on ROW CS and GT.
o Thicker cylinder head casting taken into use early in model year to strengthen head against cracking. Longer head bolts needed because of the change.
o ROW 928 CS into same VIN sequence as ROW S4. Model dropped from production during the model year at the end of 1988.
o February 1989, manual transmission only GT debuts as a more sporting version on all markets.
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1990
• Model designation: 928 S4/928 GT
• Engine displacement: 5.0 L
• Valves: 32
• Power: 316 hp/320 PS (236 kW) (S4) / 326 hp/330 PS (243 kW) (GT)
• Changes:
o GT pistons into use in S4 also resulting true 10.0:1 compression ratio for all engines.
o RDK tyre pressure monitoring system standard on all cars. Computer controlled 0-100% PSD locking differential added to both models.
o S4 no longer available with manual gearbox.
o Dual airbags now standard across all Porsche models in USA. Driver and front passenger airbag optional in LHD ROW cars, only drivers side bag available in RHD markets.
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1991
• Model designation: 928 S4/928 GT
• Engine displacement: 5.0 L
• Valves: 32
• Power: 316 hp/320 PS (236 kW) (S4) / 326 hp/330 PS (243 kW) (GT)
• Changes:
o Improvements to steering rack, power steering pump, soundproofing, front cooling flaps deleted, new style shift knob with integrated leather booth in manual gearbox cars, etc. Temperature sensors for ignition circuit monitor system moved from #4 and #8 cylinders to #3 and #7 cylinders to improve their efficiency.
o Check engine warning light added to all US models due to California regulatory demands.
o Two airbags as standard in ROW LHD models during model year production, at same time drivers side airbag standard in RHD models while passenger side bag still not available.
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1992
• Model designation: 928 GTS
• Engine displacement: 5.4 L
• Valves: 32
• Power: 345 hp/350 PS (257 kW)
• Changes:
o Engine grows to 5.4 L due to longer stroke crankshaft and different compression height and 10.4:1 ratio pistons, improved cooling in exhaust side at cylinder heads, bodywork updated with flared rear fenders and so called cup mirrors. "big black" front brakes, significantly larger than "S4" version. Stronger manual gearbox with differential driven oil pump and front mounted oil cooler.
o GTS became available in North America at February 1992 as early 1993 model with later model year VIN. These cars use same parts as 1992 ROW models and can be differentiated from true 1993 US models with separate VIN sequence and option code M718.
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1993
• Model designation: 928 GTS
• Engine displacement: 5.4 L
• Valves: 32
• Power: 345 hp/350 PS (257 kW)
• Changes:
o Cylinder block lower half studs replaced with bolts. Engine piston rings changed to limit oil consumption and pistons changed to strengthen skirt area. Minor update to clutch.
o Passenger side airbag added to RHD cars.
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1994
• Model designation: 928 GTS
• Engine displacement: 5.4 L
• Valves: 32
• Power: 345 hp/350 PS (257 kW)
• Changes:
o Connecting rods changed to stronger design part. Cabin pollen filter added. Dynamic kickdown to automatics. Wheel design changed to Cup II, RDK deleted at same time.
o First 19 US models were made already in spring of 1993, months before when normal model year change occurs in July. These M718 option cars still used previous model year parts like Cup I wheels and do not have 1994 model year updates despite using same 1994 VIN sequence.
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1995
• Model designation: 928 GTS
• Engine displacement: 5.4 L
• Valves: 32
• Power: 345 hp/350 PS (257 kW)
• Changes:
o Special model available in some ROW markets containing wider front fenders made out of steel and 8" wide front wheels. Only available with automatic gearbox, Iris blue metallic and Amazon green metallic color with Classic grey leather interior.
o Manual gearbox car production ended some months before last automatic cars were made.