This study investigates concurrent changes in cognitive workload and situation awareness during the use of full driving automation. Research shows that automation use has a negative effect on situation awareness. Driving studies posit a decline in cognitive workload when driving automation is engaged. Yet little is known about how changes in cognitive workload affects situation awareness, or vice versa, when full driving automation is used. Participants were instructed to operate a virtual reality fixed-base driving simulator in full driving automation mode. No driving input was required by participants making the driving demand minimal. Situation awareness was measured by means of the situation awareness global assessment scale. Cognitive workload was measured by means of behavioral, ocular, and neurophysiological metrics. Lower awareness was observed over time. Cognitive workload increased over time as evidenced by an increase in pupil size and oxygenated hemoglobin in the right dorsolateral prefrontal cortex. Results indicate an inverse relationship between cognitive workload and situation awareness, with increments in the former leading to reductions in the latter. Although this pattern runs counter to our hypothesis, this is consistent with prior work observing a decline in situation awareness under increasingly higher workload.