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In this paper the relationship between weight reduction and fuel economy is determined. This is executed with simulations for the three different propulsion systems ICE (internal combustion engine), hybrid system and fuel cell (FC) system. Furthermore, the three different vehicles classes compact, mid-size and SUV are considered along with two driving cycles, NEDC and HYZEM. The re-sizing of the propulsion systems according to the lighter vehicle weight to achieve the same acceleration as the basis vehicle is implemented as well. As an overall result it is established that no general value for the fuel consumption reduction per weight reduction exists. It is very important to consider all boundary conditions, especially the used driving cycle, the examined vehicle class, the type of propulsion system and a possible powertrain re-sizing. In detail the results show values between 2 and 8 % fuel consumption reduction at a 10 % weight reduction.

It is well known that an unplanned component mass increase during vehicle design creates a ripple effect of changes throughout the vehicle subsystems, which require resizing for the additional mass. This in turn, increases overall vehicle mass. And the opposite is true in vehicle mass reduction where subsystem resizing is necessary to account for an initial mass reduction enabled, for example, by a new technology. These secondary mass changes can be significant and must be considered in the mass budgeting process due to their importance to fuel consumption and greenhouse gas emission assessments. Secondary mass reduction may be modeled using subsystem mass influence coefficients-the incremental change in subsystem mass for a unit change in gross vehicle mass. This paper focuses on means to estimate influence coefficients using two methods: Analytical and Regression.