The noise level shown on your vehicle registration certificate (field U.1): how to read it, and the loudest production sports cars

Updated: 26 September 2026. The definitions refer to European legislation; the ranking values come from the official Dutch vehicle register (RDW), queried on that date.

Key points

• U.1 = stationary noise level, in dB(A). U.2 = engine speed for this measurement, in rpm. U.3 = noise level moving (drive-by), in dB(A). These codes are harmonised by Directive 1999/37/EC (EUR-Lex).
• The U.1 measurement is taken with a microphone at 0.5 m from the exhaust outlet, at 45°, with the engine in neutral (Regulation (EU) No 540/2014, Annex II).
• In our survey, production sports cars range from 80 dB(A) (Honda Civic Type R) to 115 dB(A) (Ferrari 812 Competizione) at a standstill, while their drive-by noise stays between 70 and 74 dB(A) (the most common values).

Where to find the noise level on the registration certificate

The harmonised European registration certificate may include, under code U "noise level" (Directive 1999/37/EC, Annex I, point VI):

These fields are among the directive's optional data: each state decides whether to print them. On the French registration certificate, the official specifications for two-wheeler roadworthiness testing define U.1 as the "section du Certificat d'Immatriculation indiquant le niveau sonore à l'arrêt (en dB)" (section of the registration certificate showing the stationary noise level, in dB) and use U.2 as the measurement engine speed (UTAC, CDC 8 indice B).

How the U.1 value is measured

Regulation (EU) No 540/2014 (Annex II, point 4.2) describes the stationary vehicle test (EUR-Lex):

• Microphone position: 0.5 m (± 0.01 m) from the exhaust pipe's reference point, at a 45° angle (± 5°) to the axis of the exhaust outlet, level with the outlet but no less than 0.2 m from the ground.
• Conditions: gearbox in neutral, engine at normal temperature, bonnet closed; background noise at least 10 dB(A) below the measured level; at least three measurements.
• Engine speed: 75% of the maximum power speed S if it is equal to or below 5,000 rpm; 3,750 rpm if S is between 5,000 and 7,500 rpm; 50% of S above 7,500 rpm. This is why 3,750 rpm appears so often in field U.2.

U.1 is not a limit

European type-approval limits apply to the drive-by test: 68 to 72 dB(A) in phase 3 for passenger cars depending on the power-to-mass ratio, applicable to all first registrations from 1 July 2026 (Annex III of Regulation 540/2014). The U.1 value, taken 50 cm from the outlet, is much higher: our survey ranges from 80 to 115 dB(A) for cars that are all type-approved.

U.1 mainly serves as a reference for later tests of the vehicle at a standstill: the French roadworthiness test for two-wheelers (U.1 + 7 dB), the Spanish ITV for motorcycles (document value + 4 dB(A)), the Italian revisione (carta di circolazione value, + 2 dB at an approved facility). Full details are on our page Noise cameras and car noise enforcement in Europe.

Nor is it comparable to the 85 dB(A) threshold used by French noise cameras, which applies to a moving vehicle measured at a distance: the ministry states that this dynamic measurement threshold cannot be compared with stationary type-approval values (ecologie.gouv.fr).

Ranking: stationary noise level of 25 production sports cars

Type-approval values taken from the Dutch vehicle register (RDW), for cars of this model registered in the Netherlands. "Drive-by" corresponds to field U.3. When the same model has several values depending on the variant, the most common value is shown and the spread is noted.

Source for all lines: RDW Open Data, datasets "Gekentekende_voertuigen" (m9d7-ebf2) for the model and type-approval, and "Gekentekende_voertuigen_brandstof" (8ys7-d773) for the fields geluidsniveau_stationair (U.1), toerental_geluidsniveau (U.2) and geluidsniveau_rijdend (U.3). Public domain data, updated on 26/09/2026. "Drive-by": the most common value among the cars for which the field is populated.

Method and limits

• Data: official Dutch register, queried on 26/09/2026. For each model, we used the commercial name, the root of the EU type-approval number and the net power output, then counted the noise values of all matching cars.
• What these are: type-approval values recorded by model and variant, not measurements taken on each individual car.
• Variations: the same model may have several values depending on the variant, body style or year; these are flagged in the table. Models whose values were too scattered to summarise honestly (notably the Lamborghini Huracán and Aventador) were excluded.
• Names: we use those from the register (including power and displacement) rather than generation codes, so that each line can be checked.
• Scope: the value for your car is the one on your registration certificate; that is the value that counts.

Key takeaways

Field U.1 describes the noise measured right next to the exhaust, with the engine stationary and at the speed shown in U.2. It varies widely from one model to another (a 35 dB(A) spread in this survey) without saying anything about compliance: all these cars were type-approved with drive-by noise between 70 and 74 dB(A) (the most common values in the register). U.1 is mainly a reference value, useful for comparing a vehicle with its original condition during a stationary test, where such a test exists.

On a valved exhaust system, closed-valve mode keeps a sound close to the original: that is the reference state for stationary tests. For the state of noise enforcement in each country, see noise cameras in Europe: a country-by-country update. Rog also publishes a guide per model to help you choose your exhaust.

Frequently asked questions

What does field U.1 of the registration certificate mean?
This is the vehicle's stationary noise level, in dB(A), measured during type approval at 0.5 m from the exhaust outlet. Field U.2 shows the engine speed (rpm) at which this measurement was taken.

Does a U.1 value of 100 dB(A) mean the car is illegal?
No. U.1 is a reference measurement taken right next to the exhaust, not a limit. European type-approval limits (68 to 75 dB(A) depending on the phase and category) apply to the drive-by test, measured at a distance.

What is the U.1 value used for during a test?
It serves as a reference whenever a test measures stationary noise: for example in the French roadworthiness test for two-wheelers (U.1 + 7 dB), the Spanish ITV for motorcycles (+4 dB(A)), or the Italian revisione. For cars, the French roadworthiness test remains auditory.

Sources

All accessed on 26/09/2026.

1. EUR-Lex, Directive 1999/37/EC on registration documents for vehicles, Annex I (codes U.1, U.2, U.3): https://eur-lex.europa.eu/legal-content/FR/TXT/HTML/?uri=CELEX:31999L0037
2. EUR-Lex, Regulation (EU) No 540/2014, Annex II (stationary test, point 4.2) and Annex III (limit values): https://eur-lex.europa.eu/legal-content/FR/TXT/HTML/?uri=CELEX:32014R0540
3. UTAC, cahier des charges CDC 8 indice B, sound level measuring devices (12/03/2024): https://www.utac-otc.com/Categorie_L/Documents/CDC8B%20-%20Dispositifs%20de%20mesure%20du%20niveau%20sonore%20-%2020240312.pdf
4. Ministère de la Transition écologique, "Expérimentation de radars sonores" ("Noise-camera trial"): https://www.ecologie.gouv.fr/politiques-publiques/experimentation-radars-sonores
5. RDW Open Data, "Gekentekende_voertuigen" (registered vehicles): https://opendata.rdw.nl/Voertuigen/Open-Data-RDW-Gekentekende_voertuigen/m9d7-ebf2
6. RDW Open Data, "Gekentekende_voertuigen_brandstof" (registered vehicles, fuel): https://opendata.rdw.nl/Voertuigen/Open-Data-RDW-Gekentekende_voertuigen_brandstof/8ys7-d773
7. Ministero delle Infrastrutture e dei Trasporti (CSRPAD), limits at the revisione: https://www.csrpad.it/csrpad/it/revisioni/limiti-vigenti
8. Ministerio de Industria y Turismo, ITV manual v7.8: https://industria.gob.es/Calidad-Industrial/vehiculos/itv1/Manual%20de%20procedimiento%20de%20inspecci%C3%B3n/Manual%20de%20procedimiento%20de%20inspeccion%20de%20estaciones%20ITV-V%207.8.pdf