Time lags are known to reduce performance in human-in-the-loop control systems. Performance decrements for human-in-the-loop control systems as a result of time lags are generally associated with the operator’s inability to predict the outcome of their control input and are dependent upon the characteristics of the lag (e.g., magnitude and variability). Further, the effects of variable time lags are not well studied or understood, but may exacerbate the effects on human control actions observed with fixed lags. Several studies have demonstrated mechanisms that can help combat the effects of lag including adaptation, mathematical predictors (e.g., filters), and predictive displays. This experiment examined the effects of lag and lag variability on a simulated driving task, as well as a possible mitigation (predictive display) for the effects of lag. Results indicated that lag variability significantly reduced driving performance, and that the predictive display significantly improved performance for both fixed and variable lags.