Front under run protection device (FUPD) is a regulatory requirement for passive safety of N2 & N3 category vehicle. This device gives effective protection for small vehicles (M1 or N1 category) against under running of big vehicles (N2 & N3 category) in the event of a frontal collision. FUPD generally consists of the front under run protector (FUP) and its mounting structure. As the compliance load target for N3 category is high, the FUP required achieving regulation target need to have high rigidity. This increases its size and hence the weight, Increase in weight has impact on payload and cost. To curtail the weight of FUP, in general Aluminum with higher strength is in use, but use of Aluminum increases the cost. So the main challenge in FUPD design is to achieve the design with optimal system weight & cost.This paper describes the methodology of designing cost effective FUPDs for an N3 category vehicle, without changing the current mounting structure, by using high strength steel thereby maintaining component weight at par with Aluminum FUP. This cost & weight effective FUPD design process involved preliminary design calculation, component design, digital evaluation in LS-Dyna and physical bench test. After establishing co-relation among design calculation, physical & digital validation, design was finalized and found 2% lesser in weight and 20% lesser in cost than existing design. This new design then implemented on vehicles.