Lean premixed compression ignition low-temperature combustion promises to simultaneously reduce NOx and PM emissions while suffering a moderate penalty in fuel consumption. Similarly, opportunities exist to develop rich combustion strategies which can provide the necessary exhaust constituents for aggressive regeneration of a lean NOx trap (LNT). The current work highlights the development of lean and rich premixed compression ignition combustion strategies. It is shown that the lean premixed compression ignition combustion strategy successfully operates with low NOx and smoke, at the expense of a 5% increase in fuel consumption over conventional diesel operation. The rich premixed compression ignition combustion strategy similarly operates with low NOx and smoke, and produces enough CO (up to 5% by volume in exhaust) for aggressive regeneration of an LNT.