Abstract—In recent years a new technological revolution inrear lighting designoccurred. This important change is due tothe integration of LED sources, innovativeoptical systems,newmaterials, along withthe growth of virtual simulation tools. Alltheseenhancementshave enabled designers to create attractive lampswith three-dimensionalshape and large elements that provideergonomiclighting.Nevertheless, these systems are optically inefficient andvery complex;in fact they contain several lighting sources,electrical components, heatsinks and plastic elements. Theseconsiderations imply two critical issues: a considerableincrease of productioncosts andadecreaseofsustainabilityofthelamps(energyandmaterials consumption).

The purpose of this paper is to investigateinnovative optical solutions for signaling functions, such as light guides,diffuser moldingcompounds,byfocusingontwostrategicandcompetitive optical aspects: visual comfort and luminousefficiency.

The first part of this workis devoted to homogeneity analysis; anew integrated rating, combining physical andsubjective aspects,is proposed.Thenthesafetyfeaturesofthesesystemsaretakeninto account,and photometrical performances are evaluated. Amorecomprehensivemodel of lighting efficiency is obtainedcorrelating the achieved results with power consumptionand costs.The improvement of optical performances together with themaintaining of a nice appearance are explored. Finally, the paperpresents OLED-lightingsystems; this technology has high potential forfutureautomotiveapplications and could reach the tradeoff betweenstyle and efficiencythat marketrequires.

Keywords: Visual comfort, uniformity, isotropy,luminous efficiency,sustainability, life cycle,OLED