Automotive electronics, solid-state-lighting, and solar cells need have to operate under harsh circumstances, either by the kind of environment they operate in, such as automotive electronics under the hood, or by the long durations of exposure. In both cases traditional lifetime assessment methods are failing: The accelaration factors, who are key to accelerated lifetime testing, are becoming to small as the operational conditions are nearing the testing conditions (automotive electronics under the hood) or are insuffiently large to obtain acceptable testing times (SSL and Solar). Trends and drivers for this are described . The some fundamental issues are presented for the mission profiles, failure and degradation mechanisms, as well as the acceleration factors. Ideas to overcome the presented limitations are shown in a combined testing-modelling scheme with some examples highlighting aspects of these ideas. ©2010IEEE.