The needs and factors affecting the successful operation of data acquisition equipment in real world sub-zero testing procedures are outlined and a number of minimal and desirable performance requirements, that should be satisfied to provide successful operation under subzero operating conditions, are set forth. While these factors and requirements are common to most cold weather test situations, this paper concentrates on vehicular applications.Cold weather (below 0°C or 32°F) testing, as with other experimental procedures, involves the collection of test data, both subjective and objective, to be subsequently condensed and analyzed. To make the optimal use of a short (two or three month) sub-zero testing season, sophisticated data acquisition equipment is often employed for making and recording quantitative measurements. These systems are often the testing group's laboratory or mobile instruments, intended for use in more moderate temperature conditions, perhaps with minor alterations to attempt to improve low ambient temperature performance. Given the combination of urgency, resulting from the condensed test time available, and often remote and isolated test locations, malfunctions or failures of any equipment, in particular complex data acquisition system components, can be much more serious and detrimental than under most other test circumstances.With the diverse demands of sub-zero testing, such as the need for absolute reliability, intensive use, and severe ambient conditions, it is imperative that specific conditions of operation be defined and that equipment be initially designed or modified sufficiently to meet those conditions, in order to better assure successful instrumentation operation.A comprehensive listing of operating conditions and criteria for sub-zero data acquisition systems follows, along with an analysis of each and recommendations for counter-measures to be developed or applied to permit “acceptable” system performance. These conditions and criteria have been developed during years of practical experience and work in sub-zero conditions using different testing procedures, with a wide assortment of test vehicles and devices.