Internal combustion engines developments are driven by emissions reduction and energetic efficiency increase. To reach the next standards, downsized/downspeeded engines are required to reduce fuel consumption and CO2 emissions. These techniques place an important demand on the charging system and force the introduction of multistage boosting architectures. With many possible arrangements and a large number of parameters to optimize, these architectures present a higher complexity than current systems. The objective of this thesis has thus been to investigate the potential of two-stage boosting architectures to establish, for the particular case of passenger car downsized/downspeeded Diesel engines, the most efficient solutions for achieving the forthcoming CO2 emissions targets.To respond to this objective, an exhaustive literature review of all existing solutions has first been performed to determinate the most promising twostage boosting architectures. Then, a new matching methodology has been defined to optimize the architectures with, on the one hand the development of a new turbine characteristic maps representation allowing straight forward matching calculations and, on the other hand, the development of a complete 0D engine model able to predict, within a reduced computational time, the behavior of any boosting architecture in both steady state and transient operating conditions. Finally, a large parametric study has been carried out to analyze and compare the different architectures on the same base engines, to characterize the impacts of thermo-mechanical limits and turbocharger size on engine performance, and to quantify for different engine development options their potential improvements in terms of fuel consumption, maximum power and fun to drive.As main contributions, the thesis provides new modeling tools for efficient matching calculations and synthesizes the main trends in advanced boosting systems to guide future passenger car Diesel engine development. ResumenLos desarrollos actuales en el campo de los motores de combustión interna alternativos están principalmente motivados por la reducción de las emisiones contaminantes y el aumento de la eficiencia energética. Cumplir con los nuevos estándares para automoción requiere una reducción en el consumo de combustible y en las emisiones de contaminantes, y para ello resulta imprescindible el uso de motores downsized and downspeeded. El empleo de dichas técnicas impone unos requisitos de exigencia elevados al sistema de renovación de la carga y obligan a la introducción de arquitecturas de sobrealimentación multi-etapa. Debido a la gran variedad de configuraciones posibles y al elevado número de parámetros a optimizar, esas arquitecturas presentan una mayor complejidad que los sistemas actuales. Por tanto, el objetivo principal de esta tesis ha sido investigar el potencial de las arquitecturas de sobrealimentación de doble etapa para establecer, en el caso particular de los motores downsized and downspeeded, las soluciones más eficientes qu...