Porsche 928 (1991)

Estimated running costs and MOT pass rates from 42 MOT tests in 2024.

Annual Cost

£2,888

£241/month

MOT Pass Rate

76%

Average

Road Tax

£375

Estimated/year

Est. Insurance

Grp 35-50

4957cc Petrol

Check Carefully

76% pass rate, £2,888/year to run. 6 points below average.

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Petrol4957cc35 years old42 tests127k miles avg

Annual Running Costs

Fuel (Petrol, 4957cc)

~30 mpg

£1,958

Road Tax

Pre-2001 engine size rate

£375

MOT Test

£55

Predicted Repairs

£500

Total per year£2,888

Per month£241/mo

Per week£56/wk

Estimates based on 7,400 miles/year (UK average), petrol at 174.57p a litre (GOV.UK weekly average, week of 19 October 2026), GOV.UK road tax rates and repair likelihood from MOT data. Insurance not included.

Reliability Verdict

76% MOT pass rate(Average)

0%All-model avg: 82%100%

Average reliability. Expect some repairs as it ages. That's 6 points below the average of 82% across all models in our data. It falls below the Porsche brand average of 92%.

76% of MOT tests on Porsche 928s from 1991 ended in a pass in 2024, when they were about 33 years old. That's based on 42 tests across the UK, retests included. The average mileage recorded at those tests was 127,119 miles.

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How Does It Compare?

Rank among 1991 models118th of 172(bottom half)

Rank among Porsche models268th of 272(bottom 2%)

vs average of all models-6%(82% avg)

vs 1991 models average-3%(79% avg)

vs Porsche average-16%(92% avg)

Mileage Analysis

127,119

Average miles

244,200

Expected for age

The average 1991 Porsche 928 had 127,119 miles on the clock at its 2024 MOT, which is below the expected 244,200 miles for a 33-year-old car. This suggests lighter use than average, which generally means less wear on major components.

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Porsche 928 by Year

Year	Pass Rate	Tests	Avg Mileage
1995	80%	153	68,198 mi
1994	91%	79	81,080 mi
1993	96%	50	102,665 mi
1992	90%	41	101,109 mi
1991	76%	42	127,119 mi
1990	88%	52	97,889 mi

Similar Cars to Consider

Jaguar XJS

1990 · 5343cc Petrol

£2,738/year

82%

+6%

Mercedes 500

1991 · 4973cc Petrol

£2,738/year

87%

+11%

Mercedes SL

1991 · 4973cc Petrol

£2,738/year

86%

+10%

Jaguar XJ

1990 · 5345cc Petrol

£2,738/year

86%

+10%

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About the 1991 Porsche 928

The 1991 Porsche 928 is a luxury car. Our records list a 4957cc petrol engine, though engines vary between versions. 42 MOT tests were recorded on this model in 2024, making it a rare model on UK roads. Among all models from 1991, the average MOT pass rate is 79%, and this model falls short of that benchmark.

With an average of 127,119 miles recorded at its 2024 MOT tests, Porsche 928 owners tend to use this car less than the typical driver.

1991 Porsche 928 Fuel Costs

The 4957cc petrol engine is on the larger side, so fuel won't be this car's strong point. Expect around 30 mpg in mixed driving, which works out to roughly £1,958 per year with petrol at 174.57p per litre (GOV.UK weekly average, week of 19 October 2026; based on 7,400 miles per year).

What does it cost to own a 1991 Porsche 928?

Total estimated annual running cost is £2,888 (£241/month), broken down as £1,958 fuel, £375 road tax, £55 MOT, and £500 predicted repairs. Repair costs are moderate, reflecting the 76% pass rate. Keeping on top of servicing will help avoid surprises.

Buying a Used 1991 Porsche 928

At 35 years old, the Porsche 928 is firmly in budget territory. Purchase prices are low, but check for rust, worn suspension bushes, and electrical gremlins. A full service history is especially valuable at this age. Note: with only 42 tests in our data, these figures should be treated as indicative rather than definitive.

Common Issues to Watch For

These are typical issues for cars of this age, fuel type and engine size, not faults recorded on this model's MOT tests. Use them as a checklist when you view one.

Timing Chain / Belt

Watch out

At 35 years old, check whether the timing belt has been replaced (typically due every 5-7 years or 60,000-100,000 miles). A snapped belt can destroy the engine.

Oil Consumption

Medium risk

Larger petrol engines can develop higher oil consumption as they age. Check the oil level and look for blue smoke from the exhaust.

Rust and Corrosion

Watch out

At 10+ years, check wheel arches, sills, subframe, and brake lines for rust. Structural corrosion is an MOT failure. Prevention is far cheaper than repair.

Suspension Bushings

Watch out

Rubber suspension bushes harden and crack with age, causing knocking noises and vague handling. A full refresh costs £300-£800 depending on the car.

Clutch Wear

Watch out

With an average of 127k miles, clutch replacement may be due (typical lifespan 60,000-100,000 miles). Budget £400-£800 for a new clutch kit.

Brake Discs and Pads

Medium risk

High-mileage cars often need brake disc replacement, not just pads. A full set of discs and pads costs £200-£500 per axle.

Engine Mounts

Medium risk

Worn engine mounts cause excessive vibration and movement. Replacement costs £150-£400 per mount. Check for vibration at idle with the bonnet open.

Service History

Low risk

Always request a full service history. Regular servicing is the single best indicator of how well a car has been maintained, regardless of mileage.

Running Costs Compared

How the 1991 Porsche 928 stacks up against similar cars for estimated annual running costs, insurance group, and tax.

Car	Pass Rate	Fuel/yr	Tax/yr	Est. Ins. Group	Total/yr
Porsche 928(1991)	76%	£1,958	£375	Grp 35-50	£2,888
Jaguar XJS(1990)	82%	£1,958	£375	Grp 35-50	£2,738-£150
Mercedes 500(1991)	87%	£1,958	£375	Grp 35-50	£2,738-£150
Mercedes SL(1991)	86%	£1,958	£375	Grp 35-50	£2,738-£150
Jaguar XJ(1990)	86%	£1,958	£375	Grp 35-50	£2,738-£150

Estimates based on 7,400 miles/year, GOV.UK average pump prices for the week of 19 October 2026, GOV.UK road tax rates and MOT data. Insurance groups are our rough estimate from engine size, not official groups. Actual costs vary by driver, location, and usage.

Questions about the 1991 Porsche 928

Is the 1991 Porsche 928 reliable?

Average reliability. Expect some repairs as it ages. 76% of MOT tests on 1991 Porsche 928s ended in a pass, from 42 tests (DVSA MOT data for tests in 2024, retests included). That's 6 points below the average of 82% across all models in the same data.

How much does a 1991 Porsche 928 cost to run?

Our estimate is £2,888 a year (£241 a month): £1,958 fuel, £375 road tax, £55 MOT and £500 predicted repairs, based on 7,400 miles a year. Insurance is not included.

What is the MOT pass rate for a 1991 Porsche 928?

76% of 42 MOT tests on the 1991 Porsche 928 ended in a pass (DVSA MOT data for tests in 2024, retests included). That ranks it 118th of 172 models first registered in 1991 (bottom half).

What is the average mileage for a 1991 Porsche 928?

The average mileage recorded at MOT tests on the 1991 Porsche 928 is 127,119 miles, which is below the expected 244,200 miles for a 33-year-old car. This suggests lighter use than average, which generally means less wear on major components.