WLTP: What the Test Procedure Is, WLTC Classes and Phases

WLTP is the Worldwide harmonized Light vehicles Test Procedure: the laboratory method used to measure the emissions, fuel consumption and electric energy consumption of light-duty vehicles over a standard 30-minute speed trace, the WLTC. In the European Union it replaced the NEDC for type-approval of new light passenger and commercial vehicle types between 2017 and 2019.

What WLTP and the WLTC are

Two names are often used as if they were one. WLTP is the whole test procedure: preconditioning, soak, the driving test on a chassis dynamometer, measurement and calculation rules. WLTC (Worldwide harmonized Light vehicles Test Cycle) is only the speed-versus-time trace the vehicle is driven against inside that procedure. The procedure is published as UN Global Technical Regulation No. 15, established in the UNECE Global Registry on 12 March 2014. Its scope covers gaseous and particulate emissions, particle number, CO2, fuel consumption, electric energy consumption and electric range for light-duty vehicles (UNECE, global technical regulations registry).

The programme began in November 2007 when the UNECE World Forum WP.29 set up an informal group under its GRPE working party. A road map followed in 2009, the first formal text was adopted by GRPE in 2013, and WP.29 confirmed it in 2014 (Transport Policy, WLTP summary page). For a wider explanation of what a drive cycle is and how WLTC differs from the US FTP-75, see the drive cycle guide.

How a WLTP test is run in the laboratory

Annex XXI of Commission Regulation (EU) 2017/1151 is the EU legal text that implements the procedure; the test it defines is called the Type 1 test. Several features of the laboratory routine are set out there and are easy to miss in short explainers:

• Soak temperature and duration. After preconditioning, the vehicle is soaked for a minimum of 6 hours and a maximum of 36 hours at 23 °C ± 3 °C before the test.
• Class-specific preconditioning drive. Class 1 vehicles run the phase sequence low, medium, low, low, medium, low. Class 2 and Class 3 vehicles run low, medium, high, medium.
• A speed trace at 1 Hz. The cycle is defined second by second (1,800 seconds for Class 3), and the trace is identified by checksums so a laboratory can confirm it has loaded the correct cycle.
• Capped-speed and downscaling provisions. The regulation contains rules for vehicles that cannot follow the trace, for example because of limited top speed.
• A second, cooler test. The ATCT (Ambient Temperature Correction Test) is run at 14 °C and is listed in the regulation’s test-type table, alongside the 23 °C WLTC test.

A laboratory running such a procedure documents it as a controlled standard operating procedure (SOP); the regulation fixes the technical requirements, not the laboratory’s internal paperwork.

WLTC vehicle classes: which cycle a vehicle drives

There is no single WLTC. The regulation assigns each vehicle to a class by its power-to-mass ratio, and the class decides which phases are driven. Pmr below is rated power divided by mass in running order minus 75 kg, in W/kg (Regulation (EU) 2017/1151, Annex XXI, Sub-Annex 1).

Class	Rule	Phases driven
Class 1	Pmr ≤ 22 W/kg	Low, medium, additional low
Class 2	Pmr > 22 and ≤ 34 W/kg	Low, medium, high, extra high
Class 3a	Pmr > 34 W/kg and vmax < 120 km/h	Low, medium, high, extra high
Class 3b	Pmr > 34 W/kg and vmax ≥ 120 km/h	Low, medium, high, extra high

The resulting cycle is called the “applicable cycle” in the regulation. The Class 3b cycle, which most passenger cars follow, runs 1,800 seconds and covers 23,266 m with 242 seconds spent stopped. Its four phases differ sharply in speed: the low phase peaks at 56.5 km/h with an average of 18.9 km/h including stops, the medium at 76.6 km/h (39.5 km/h average), the high at 97.4 km/h (56.7 km/h average), and the extra-high at 131.3 km/h (92.0 km/h average) (DieselNet, WLTC cycle page). The data table below sets out the Class 3b phase durations and distances and the total duration and distance for every class; the Class 3b phases sum to the 1,800-second total.

Class 3a differs from 3b only in two phases: its medium and high phases cover 4,721 m and 7,124 m, against 4,756 m and 7,162 m for 3b, giving a 23,194 m total. Class 2 totals 22,649 m in 1,800 seconds. Class 1, with its shorter three-phase cycle, lasts 1,611 seconds and covers 11,428 m (DieselNet).

Legal timeline: from the UN regulation to EU registration dates

Step	What happened	Source
12 March 2014	GTR No. 15 established in the UNECE Global Registry	UNECE
1 June 2017	Commission Regulation (EU) 2017/1151 adopted (OJ L 175, 7.7.2017), supplementing Regulation (EC) No 715/2007	EUR-Lex
1 September 2017	National authorities refuse EC or national type-approval of new types not complying, for M1, M2 and N1 class I	Reg. 2017/1151, Art. 15
1 September 2018	Same for N1 class II, III and N2. For M1, M2 and N1 class I, non-compliant certificates of conformity cease to be valid and registration, sale and entry into service are prohibited	Reg. 2017/1151, Art. 15
1 September 2019	Registration, sale and entry into service prohibition applies to N1 class II, III and N2	Reg. 2017/1151, Art. 15
Jan 2020 / Jan 2021	Regulation (EU) 2018/1832 additions, including on-board fuel and energy consumption monitoring (OBFCM), apply to new M1 types from January 2020 and N1 from January 2021, and to all vehicles a year later	Transport Policy

These dates apply to the vehicle categories named in the regulation’s Article 15, not to every vehicle everywhere. Outside the EU, adoption dates differ by jurisdiction; the dates above should not be read as a global schedule.

WLTP, RDE and older cycles

The WLTC is a laboratory test: the vehicle stays on a dynamometer. Regulation 2017/1151 also defines Real Driving Emissions (RDE) as emissions under normal conditions of use, measured on the road with a portable emissions measurement system (PEMS, Annex IIIA). RDE is a separate test (Type 1A) that complements, rather than replaces, the laboratory Type 1 test. The NEDC, which WLTP replaced for EU type-approval, is a different, older cycle. For a look at how emissions rules and measurements fit together, see the vehicle emissions guide.

Where it matters for labs and testing programmes

For an emissions laboratory, the practical points drawn from the regulation are: the cycle depends on the vehicle class, so class must be established from rated power and running-order mass before a test is planned; the 6 to 36 hour soak at 23 °C ± 3 °C constrains scheduling; the ATCT adds a 14 °C test; and cycle identification by checksum is part of verifying the setup. For fuel-economy figures quoted in vehicle specifications, the number is the result of this laboratory procedure, not a measurement of any individual driver’s consumption.

Common misunderstandings

• “WLTP is a single cycle.” The WLTC varies by class (1, 2, 3a, 3b), with different phase sets.
• “WLTP measures real-world driving.” It is a standardised laboratory procedure. On-road emissions in the EU are covered by the separate RDE test.
• “WLTP and WLTC are synonyms.” WLTC is the speed trace; WLTP is the full procedure including preconditioning, soak and calculation rules.
• “It applied everywhere on one date.” The EU introduced it in stages by vehicle category from September 2017 to September 2019, as shown above.

FAQ

What does WLTP stand for?

Worldwide harmonized Light vehicles Test Procedure. The cycle within it is the Worldwide harmonized Light vehicles Test Cycle (WLTC).

How long is a WLTP test cycle?

For Classes 2, 3a and 3b the cycle lasts 1,800 seconds (30 minutes). Class 1 lasts 1,611 seconds. This excludes the preconditioning drive and the 6 to 36 hour soak.

Which phases does the WLTC have?

Low, medium, high and extra-high for Classes 2 and 3; low, medium and an additional low phase for Class 1.

Is WLTP the same as real-world consumption?

No. It is a laboratory procedure at 23 °C (with an ATCT at 14 °C). Real-driving emissions are tested separately by RDE on the road.

What replaced the NEDC in the EU?

WLTP, through Regulation (EU) 2017/1151, phased in for type-approval and registration between 2017 and 2019.

Sources

• Commission Regulation (EU) 2017/1151 (consolidated text), EUR-Lex, eur-lex.europa.eu, read 2026-11-12.
• DieselNet, Worldwide Harmonized Light Vehicles Test Cycle (WLTC), dieselnet.com, read 2026-11-12.
• Transport Policy, International: Light-duty: Worldwide Harmonized Light Vehicles Test Procedure, transportpolicy.net, read 2026-11-12.
• UNECE, Global Technical Regulations registry (GTR No. 15), unece.org, entry read 2026-11-08.