Triumph Stag Mk1/Mk2 (1970-1977) reliability
Triumph Stag Mk1/Mk2 built before 2000: fails its MOT less often than average
Triumph Stag Mk1/Mk2 models built before 2000 fail their MOT less often than similar cars the same age. An independent inspection matters more than the wider numbers on cars this old.
Looking at a Triumph Stag Mk1/Mk2?
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Key figure
15% of MOT tests on Triumph Stag Mk1/Mk2 models built before 2000 ended in a fail (retests included), against 22% for similar cars the same age.
Most common issue
The most common MOT issue on Triumph Stag Mk1/Mk2 models built before 2000 involves fluid leaks.
Based on 1,332 tests of Stag models registered 1970-1977.
About 1 in 20 Stag Mk1/Mk2 MOTs (5.6%) failed and still hadn't passed 3 days later. That's for cars built before 2000 (over 25 years old), all fuels combined.
Based on 1,332 tests (DVSA MOT results, 2025). A fail that passed a retest within 3 days, even the same day, isn't counted. Nor is a fail with no later MOT on record.
About 1 in 40 Stag Mk1/Mk2 MOTs (2.3%) found at least one dangerous defect. These are cars built before 2000 (over 25 years old).
Based on 1,332 tests (DVSA MOT results, 2025). Dangerous is the most serious grade an MOT gives: a direct risk to road safety.
Mk1/Mk2 fail rate by age
Fail rate is the share of MOT tests that ended in a fail. Retests count as tests. How we count fail rates Build years are worked out from age, so they are approximate. Tests counted are 2025 MOTs. Highest fail rate at 25+ years old.
How the Stag Mk1/Mk2 compares
At each age below, see how the Stag Mk1/Mk2 holds up against other cars the same age. The averages combine all fuel types.
Based on 3,350 tests across 4 Triumph models, built before 2000 (over 25 years old).
Fail rate is the share of MOT tests that ended in a fail. Retests count as tests. How we count fail rates Build years are worked out from age, so they are approximate. Tests counted are 2025 MOTs.
What to check before viewing
The model's most common MOT issues, turned into things you can ask about or look for.
Leaks
Worth checkingInspect the leaks carefully and ask the seller for repair history.
Axles & Wheels
Worth checkingInspect the axles & wheels carefully and ask the seller for repair history.
Suspension bushes and joints
Worth checkingListen for knocks over speed bumps and ask about recent control-arm or anti-roll-bar work.
Steering
Worth checkingInspect the steering carefully and ask the seller for repair history.
Suspension
Worth checkingInspect the suspension carefully and ask the seller for repair history.
Vehicle-specific check
Worth checkingCheck the car’s number plate on MOT Wise to see its own MOT history and any recalls for its build years.
Other convertibles to compare
Other convertibles, with each one's figures taken at the same age as the Stag Mk1/Mk2.
- 1
Mercedes-Benz SL
Same body type, tested at the same age
- Fail rate
- 17.1%
- Still registered at 10 years
- 90.5%
No clear edge over the Triumph Stag Mk1/Mk2 on these figures.
Some figures could not be compared for these two cars. So this comparison uses the fail rate and recalls only.
5,842 MOT tests on cars built before 2000
- 2
Mazda MX-5
Same body type, tested at the same age
- Fail rate
- 27.2%
- Still registered at 10 years
- 97.6%
No clear edge over the Triumph Stag Mk1/Mk2 on these figures.
2 critical recall campaigns matching this model/build period.
16,460 MOT tests on cars built before 2000
- 3
MG B
Same body type, tested at the same age
- Fail rate
- 15.5%
No clear edge over the Triumph Stag Mk1/Mk2 on these figures.
Some figures could not be compared for these two cars. So this comparison uses the fail rate and recalls only.
2,865 MOT tests on cars built before 2000
- 4
Alfa Romeo Spider
Same body type, tested at the same age
- Fail rate
- 25.8%
No clear edge over the Triumph Stag Mk1/Mk2 on these figures.
Some figures could not be compared for these two cars. So this comparison uses the fail rate and recalls only.
1,562 MOT tests on cars built before 2000
- Fail rate
- = the share of MOT tests that ended in a fail. Retests count as tests.
- Still registered at 10 years
- = the share of cars still registered (taxed or declared off the road) 10 years after they were first registered.
Recall context
DVSA's recall list has no recalls filed under the Triumph Stag name. For the exact car, check with the maker or GOV.UK's recall checker.
What has gone wrong on Stag Mk1/Mk2 cars built before 2000
The share of petrol cars that have ever failed an MOT on each part of the car. Based on 455 cars.
Rust, which the MOT calls corrosion: 25% of these cars show rust-related issues at this age.
Check the sills, subframe and brake pipes before you decide.
Mk1/Mk2 variants compared
Stag Mk1/Mk2 variants built before 2000
The fail rate for each Stag Mk1/Mk2 variant, grouped by fuel. Each row counts fails per MOT test, the same way as the main fail rate chart.
Petrol
- STAG14.8%1,000 tests
- STAG AUTO17.2%332 tests
Most common issues on Triumph Stags of this age
This list covers every Triumph Stag built before 2000, whichever generation it is. We don't have a defect list for the Mk1/Mk2 on its own.
Most common advisories and fails
In order of the share of MOT tests that recorded each one
- 117.8%Advisory
Oil leak, but not excessive
- 210.0%Advisory
Wheel bearing has slight play
- 37.8%Advisory
Suspension arm pin or bush worn, but not moving too much
- 43.8%Advisory
Power steering has a slight leak
- 53.3%Advisory
Exhaust has a minor leak
Based on 1,436 tests
Looking at a Triumph Stag Mk1/Mk2?
Enter its number plate to see its full MOT history, risk rating and running costs.
Frequently asked questions
Built before 2000 (over 25 years old), the Triumph Stag Mk1/Mk2 (1970-1977) fails MOTs noticeably less often than typical for this age. This is based on 1,332 25+ year old MOT tests from DVSA data. Each retest counts as a test.