To enable indirect-driving maneuverability and threat detection in degraded visual environments (DVE), TARDEC’s ground DVE program is developing and testing a range of sensors and driver aid display systems. The current paper presents the first in a series of three simulator studies. It examined driver performance with two of the candidate driving aids, the Lane/Road Departure Warning System (LRDWS) and Optic Flow Enhancer (OFE), in three levels of degraded visual environment. Results indicated that the LRDWS best supported drivers in degraded visual environments, eliciting the lowest workload ratings and highest system usability ratings and facilitating faster driving in severe DVE conditions, with no apparent speed-accuracy tradeoff.