Fixed time lags within control systems are known to reduce the speed and accuracy of human-control actions. Further, the effects of variable time lags are not well-studied or understood but may exacerbate the negative effects associated with fixed time lags. Several studies have demonstrated mechanisms designed to combat the effects of time lag, which include adaptation, mathematical predictors and filters, and predictive displays. This experiment examined the effects of both fixed and variable time lag on a simulated-indirect-vision-driving task, as well as a possible mitigation (predictive display) for these effects. Results revealed that variable time lag significantly increased average lane offset more than fixed time lag, which indicates a decrease in driver accuracy. A predictive display significantly reduced lane offset and increased vehicle speed for both fixed and variable time lags. The predictive display also resulted in lower reports of operator workload. These results revealed the negative performance affects of variable time lag and demonstrated the utility of a predictive display to overcome the negative performance effects associated with fixed and variable time lags.