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A new way of measuring efficiency

WLTP – A new standard

The new Worldwide harmonised Light vehicles Test Procedure or WLTP is a new way of measuring emissions standards for cars. It replaces the former NEDC (New European Driving Cycle) procedure in place since 1997. 

These are the three main factors affecting the test 

Cars with more air resistance need more fuel. The more aerodynamic it is, the less air resistance it has. Small changes in a car’s aerodynamics can impact its long-term efficiency.

Tyre Rolling Resistance
When you drive, rolling resistance works to reduce your efficiency through tyre deformation. That’s why it’s important to design tyres to be as efficient as possible.

Heavy things require more energy to move. So, the lighter the car, the less fuel it uses. Lightness simply equals efficiency, and it’s also useful at improving car handling.

What you need to know 

It’s all about accuracy and relevance. The same test applies to lots of different ways, all around the world. It’s one of the biggest changes ever in the car industry. 

More realistic driving cycles 

Stricter car set-up and analysis 

Accounts for optional equipment 

More accurate temperatures 

What the new standard looks like 

Regulation timeline for EU:1998-08/1709/17 new engine approvals (09/18 all vehicles)
Optional equipment: Not considered Considered (aerodynamics, tyre rolling resistance, mass) 
Phases / Starting temperature: “Urban / Extra-Urban” Cold Start “Low / Medium / High / Extra-High” Cold Start 
Duration / Distance: 1.180 s / 10.966 m 1.800 s / 23.274 m 
Speed: 120 km/h maximum | 33,6 km/h average 132 km/h maximum | 46,5 km/h average 
Idle time: 295 s 234 s 
Acceleration: 1,04 m/s2 maximum 1,58 m/s2 maximum 

Real driving emissions at a glance. 

In addition to WLTP, since September 2017 measurements in Europe have been made according to the RDE test procedure. RDE stands for "Real Driving Emissions". In contrast to NEDC and WLTP, emission measurements are not carried out on the test bench but in the running traffic. The determined pollutant emissions (NOx and particulate matter) while driving in the road are called real emissions.

In the RDE measurement, a route mix consisting of one-third of urban roads, rural roads and motorways, with random acceleration and deceleration, is driven. The average speed on the urban roads is between 15 and 40 km/h and a maximum of 60 km/h, on the rural roads between 60 and 90 km/h and on the motorway between 90 km/h and 145 km/h.

The vehicle is equipped with a PEMS (portable emission measurement system) measuring box. This device measures pollutant emissions (NOx, CO, CO2) and particles (PN). The journey takes between 90 and 120 minutes. The outside temperature must be between -7 and +35 °C, the air conditioning system can be switched on.

The new consumption values FAQs 

What are NEDC, WLTP and RDE?
NEDC ("New European Driving Cycle") refers to a test realised on  a test bench that has been used throughout Europe since 1992 to measure the exhaust emissions and fuel consumption of passenger cars and light commercial vehicles.

NEDC has been replaced by the globally standardised WLTP ("Worldwide Harmonized Light-Duty Vehicles Test Procedure"). The new method is intended to measure the consumption of a vehicle more realistically and is based on a modified test cycle with stricter test specifications.

In addition to WLTP, emissions in Europe are to be determined in accordance with the RDE ("Real Driving Emissions") test procedure by carrying out the measurements on the road.

What is the difference between WLTP and RDE?
While WLTP uses 30 minutes on a chassis dynamometer under standardised conditions,  the RDE test takes place on public roads. In the RDE measurement, a route mix with random acceleration and deceleration is used, which takes between 90 and 120 minutes.

When do WLTP and RDE apply?
Since September 2017, the transition to WLTP and RDE has been gradual. From September 2018, the WLTP test procedure will be mandatory for all newly registered vehicles, as well as the limitation of the particle number (PN) in RDE. From September 2019, an additional RDE limit value for nitrogen oxides (NOx) will be mandatory for all new registrations.

What does WLTP mean for me?
The values ​​determined by the WLTP test method are intended to reflect consumption and CO2 and exhaust emissions more realistically. This may mean that higher fuel consumption and CO2 emissions are to be reported for vehicles with internal combustion engines. The individual choice of engine and optional equipment will also affect fuel economy and CO2 levels. Depending on national legislation, this may also result in higher CO2 taxes.

How does SEAT implement the WLTP specifications?
From September 2018, all SEAT models will be successively converted to the WLTP test procedure.

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