Dilute spark ignition engine combustion offers a promising method of improving fuel efficiency and reducing engine-out emissions and yet is not currently feasible owing to high levels of cyclic variability under highly dilute homogeneous operation. The deterministic nature of the undesirable cycle-to-cycle variations in combustion heat release implies that appropriate control schemes should yield significant reductions in cyclic variability, making it possible to use higher levels of charge dilution in production engines. A novel analysis approach is used to predict the improvement in fuel conversion efficiency that could be expected with effective control. Additionally, this analysis gives some insight into the effect of spark timing on the dynamics and controllability of the system.