The figure below shows the emissions of ISE's gasoline and diesel hybrid systems as compared with the emissions of conventional transit buses and competing hybrids.

ISE's gasoline hybrid drive system is the product the Company offers to customers who require the greatest reductions in emissions. The first prototype bus using this system was certified by the ARB that it produces only 0.4 grams of NOx per brake-horsepower hour, and practically zero particulate matter. As a result, in October 2003 this became the first hybrid system certified by the ARB for sale in California.

References:

1. California Code, Title 13, Section 1956.2, (b), (1)

" Alternative fuel" means natural gas, propane, ethanol, methanol, gasoline (when used in hybrid electric buses only), hydrogen, electricity, fuel cells, or advanced technologies that do not reply on diesel fuel. Alternative fuel also means any of these fuels used in combination with each other or in combination with other non-diesel fuels.

2. California Environmental Protection Agency, Air Resources Board, Executive Order A-359-0001, New On-Road Heavy-Duty Engines

• Use of a smaller diesel engine (Cummins ISB02 5.9 liter engine), which helps to reduce fuel consumption, emissions, and noise.
• Electrically-driven power steering, braking, and air conditioning accessories, which are more efficient than the engine-driven accessories used in conventional vehicles and competing hybrid drive systems, and which allow the engine to be stopped without loss of accessory functionality.
• Advanced control system featuring an automatic engine start/stop algorithm, which shuts off the engine every time the vehicle stops. This results in further improvements in fuel economy and emissions.
• A choice between ultracapacitors, which are more efficient than competing battery-based energy storage subsystems, and advanced nickel sodium chloride Zebra batteries, which carry more energy per unit weight than the batteries used in competing hybrid drive systems.