The ISL G spark ignited natural gas engine meets 2010 U.S. Environmental Protection Agency (EPA) and California Air Resources Board (CARB) emission standards.  The engine is based on the 8.9 liter diesel automotive (ISL) platform and shares many installation options with the diesel counterpart.

The ISL G features stoichiometric EGR combustion technology with spark ignition. Stoichiometric EGR combustion creates an oxygen free exhaust, enabling the use of maintenance-free three way catalyst after-treatment.  The ISL G offers performance benefits as well, with over 30% more torque at idle than its predecessor the C Gas Plus, the same rated speed as the ISL diesel and improved efficiency.