Porsche 911 1999: MOT failure rate for its age

23.2% of 3,885 MOT tests of the Porsche 911 first registered in 1999 failed at the first attempt (2019–2024; retests excluded). Against this model's own normal rate at the same ages the index is 110.7 (95% CI 103.5–117.9; 100 = normal for this model at that age): the 1999 Porsche 911 fails more often than other build years of the same model at the same age. This is a rough estimate from a smaller sample.

Porsche 911 built in 1999 at a glance
Measure	Value	Unit	Compared with	Years	Tests
Failed first time	23.2	%	all ages tested	2019–2024	3885
Index against this model at the same age (95% CI 103.5–117.9)	110.7	index	100 = normal for this model at that age	2019–2024	3885
Rank among this model's 23 build years	22	of 23	1 = fails least for its age	2019–2024	3885
Tested in 2024	230	tests	median 92,765 miles	2024	230

Built 1999 against Porsche 911 normal for the age: first-time MOT failure share at each age, age 20: 24.2% vs 21.7%; age 21: 22.3% vs 20.2%; age 22: 23.1% vs 20.9%. Axis from 0% to 30%. DVSA MOT bulk data, 2019–2024.

Check a 1999 Porsche 911 by registration · All Porsche 911 MOT statistics · Download the build-year table (CSV)

Data release dvsa-2024-v2 (24 Sep 2026) · page updated 30 Sep 2026 · full dataset (v5).

How does the 1999 Porsche 911 fail at each age?

Cars built in 1999 were tested at ages 20 to 22 between 2019 and 2024. Each row compares their first-time failure share with what this model normally shows at that age, after allowing for the overall failure level of each test year.

Porsche 911 built 1999: first-time MOT failure by age, against the model's normal rate at that age (2019–2024)
Age	Tests	Failed, %	95% interval	Normal for this model at that age, %	Index (100 = normal)
20	1,359	24.2	22–26.6	21.7	111.4
21	1,176	22.3	20–24.7	20.2	110.2
22	1,350	23.1	20.9–25.4	20.9	110.3

Source: DVSA MOT bulk data · Window: 2019–2024 · n = 3,885 (initial tests) · Method: normal rate = this model's first-time failure share at that age across its build years (cells of 400+ tests), adjusted for each test year's overall level; cells of 30+ tests, under 500 marked rough · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV

What fails most on the 1999 Porsche 911?

The most common failure group on cars built in 1999 is lamps, reflectors and electrical equipment: 20.2 items per 100 first tests, against 9.4 across all build years of the Porsche 911. These counts are not age-adjusted: cars built in 1999 were tested at ages 20 to 22.

Failure items per 100 first tests, Porsche 911 built 1999 against the Porsche 911 in all build years (2019–2024, not age-adjusted)
Failure group	Built 1999, per 100	All build years, per 100	Items
Lamps, reflectors and electrical equipment	20.2	9.4	1,342
Brakes	10.2	4	681
Visibility	5.9	3.6	392
Suspension	5.8	2.9	383
Noise, emissions and leaks	5.5	2.5	366

Source: DVSA MOT bulk data · Window: 2019–2024 · n = 6,653 (initial tests of this build year) · Method: failure items grouped by DVSA's top-level defect groups, per 100 initial tests; groups with 30+ items · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV

How does 1999 compare with the years around it?

Among the 23 published build years of the Porsche 911, 1999 ranks 22 (1 = fails least for its age). 1998: index 99.4. 2000: index 106.1.

Porsche 911 build years: index against the model at the same age (2019–2024)
Build year	Index (100 = normal)	95% interval	Verdict	Tests
1998	99.4	90.5–108.4	no different (rough estimate)	2,213
1999	110.7	103.5–117.9	worse (rough estimate)	3,885
2000	106.1	98.9–113.2	no different (rough estimate)	3,975
2001	108.6	103.4–113.8	worse	7,933
2002	106.0	102.2–109.9	worse	14,566
2003	109.4	105.6–113.2	worse	15,833
2004	100.6	96.7–104.5	no different	14,747
2005	93.6	90.0–97.2	better	17,136
2006	102.6	98.7–106.5	no different	17,235
2007	92.8	88.7–97.0	better	14,840
2008	97.3	92.2–102.5	no different	11,300
2009	99.7	93.6–105.9	no different	8,853
2010	92.2	86.5–97.9	better	10,502
2011	88.6	81.7–95.5	better	7,759
2012	102.4	95.3–109.5	no different	9,392
2013	90.1	82.4–97.9	better	7,779
2014	93.3	85.9–100.7	no different	9,545
2015	90.1	82.8–97.4	better	10,486
2016	91.2	83.7–98.7	better	10,584
2017	92.6	84.8–100.4	no different	10,218
2018	112.6	103.3–121.9	worse	9,034
2019	99.7	89.7–109.7	no different	7,188
2020	89.4	75.0–103.9	no different (rough estimate)	3,118

Source: DVSA MOT bulk data · Window: 2019–2024 · n = 228,121 (initial tests) · Method: observed failures against those expected for the same model at the same ages, test-year level adjusted; verdict follows the printed one-decimal bound · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV

How to cite this page

MOT Risk Index (2026). Porsche 911 1999 MOT statistics (data release dvsa-2024-v2; full dataset motriskindex-families-2024-v5, DOI 10.5281/zenodo.22975051), updated 30 September 2026. motriskindex.co.uk/cars/porsche-911/1999/

How every figure is calculated: methodology. Age, test year and build year are tied together (age = test year − build year), so the test-year level is taken as observed, not estimated.

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