CLTC

CLTC (China Light-Duty Vehicle Test Cycle) is China's official standardised fuel consumption and driving range test standard developed for light-duty internal combustion engine (ICE) and new energy vehicles. Replacing the previously utilised NEDC (European standard), this standard is derived from big data acquisition, analysis, and clustering of 24/7 real-world driving data from thousands of vehicles across representative Chinese cities (such as Beijing, Guangzhou, and Chengdu). CLTC is designed to more accurately reflect vehicle energy consumption and range performance under typical Chinese driving conditions, characterised by urban congestion, frequent stop-and-go driving, and diverse road environments.

Core Technical Architecture and Test Driving Cycles

CLTC's technical framework primarily comprises three typical driving phases, dynamic speed profile curves, and stringent laboratory test bench protocols. 

Division of Three Typical Driving Phases and Big Data Construction (Three Typical Driving Phases & Big Data Construction):

The total duration of the CLTC test cycle is 1,800 seconds, covering a total distance of approximately 14.48 kilometres with an average speed of 28.9 km/h and a top speed of 114 km/h. The test is scientifically structured into three distinct phases: Phase 1 (low-speed phase, simulating congested city-centre commutes with frequent stop-and-go driving), Phase 2 (medium-speed phase, simulating flowing traffic on urban expressways and ring roads), and Phase 3 (high-speed phase, simulating suburban or highway cruising). Derived from hundreds of millions of kilometres of real-world driving data, these test cycles deliver high local representativeness. 

Dynamometer Simulation Testing and Environmental Control (Dynamometer Simulation Testing & Environmental Control):

Conducted under standard ambient temperatures (typically around 23°C), the test vehicle is mounted on a chassis dynamometer (rolling road). Test drivers strictly follow computer-generated, second-by-second speed-time profiles to operate the throttle and brakes. During this process, exhaust emissions and fuel consumption are precisely measured for ICE vehicles, while battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) undergo continuous charge-discharge cycles from a full charge until the battery is completely depleted, thereby calculating the official CLTC driving range and energy consumption per 100 km. 

Safety Specifications and Physical Limitations

Strictly Prohibiting Equating Nominal CLTC Range Directly with High-Speed or Extreme Cold Range (Prohibiting Equating CLTC Range Directly with High-Speed or Extreme Cold Range): 

Owing to CLTC's lower average speed and substantial proportion of idling and regenerative braking phases, its test results are typically higher than actual range achieved during continuous highway driving. Motorists must not blindly embark on long-distance interstate highway journeys based solely on nominal CLTC figures without planned charging or refuelling stops. Real-world range will degrade significantly under harsh conditions, such as freezing winters with the cabin heater running or scorching summers with high air-conditioning loads.

Strictly Prohibiting Manufacturers from Utilizing Calibration Loopholes for Targeted Optimization in Lab Tests (Prohibiting Manufacturers from Utilizing Calibration Loopholes for Targeted Optimization in Lab Tests): 

As a mandatory national energy efficiency compliance standard, the authenticity of CLTC test data directly impacts consumer interests. Car manufacturers are strictly prohibited from using defeat software tailored specifically to game the CLTC speed profile on dynamometers or fitting non-standard, ultra-low rolling resistance tyres on test vehicles. Carmakers must ensure that standard mass-production units delivered to consumers exhibit energy efficiency performance that remains highly consistent and authentic to officially homologated data.