Consideration on the Implications of the WLTC - (Worldwide Harmonized Light-Duty Test Cycle) for a Middle Class Car

According to ICCT (The International Council on Clean Transportation), in the past decade could be observed a trend that becomes dangerous: the gap between consumption and pollution in real life and those reported by manufacturers. It is estimated that, if in 2001 the difference between the theoretical and the real consumptions was 7-8%, 10 years after these difference are 3-4 times higher. For example, in 2013 was found a difference of 31% for private cars and 45% for company cars, which means an average increase of 38% of CO2 emanations in comparison with the real ones. Therefore, to eliminate these discrepancies, in 2017 the European Union intends to adopt a new cycle and a new test procedure called WLTP (Worldwide Harmonized Light Vehicles Test Procedures). The new procedure has consequences for CO2 emissions target of NEDC homologation cycle for 2020-2021 (95 g CO2 / km). As a result, the new target based on the WLTC test cycle is 100 g CO2 / km for 2020. If the ambient temperature during testing is also modified for WLTP procedure (up to 14°C instead of 23°C), an additional correction of 2 g CO2 / km would be appropriate in terms of 102 g CO2 / km objective. Starting with 2020, all new vehicles will be tested only with WLTP and the CO2 emission targets should met by this procedure. It is necessary to translate the NEDC cycle target of 95 g CO2 / km in an equivalent objective based on WLTP Since the current test cycle requires more severe transient regimes, at least as a percentage, it imposes a more rigorous approach of engine calibration methods in parallel with a new development strategy for powertrains. The main directions will be: - use of hybrid powertrains groups (HPG) including a continuously variable transmission (CVT); - energy optimization of these HPG by adopting new admission and combustion processes for the mixture; - optimization of powertrain tuning with the vehicle in order to preserve the dynamic performances. This paper analyzes by modeling the midsize car’s available reserves to achieve the target referenced above. The results will be useful for the automotive specialists and car manufacturers.