In accordance with example implementations, a vehicle includes a body, an engine within the body, and at least one exhaust tube extending from the engine and having a particulate filter fluidly coupled to the exhaust tube to receive exhaust material from the exhaust tube. The vehicle also has at least one air injection pipe having a first end with an inlet arranged to receive air flow entering the body while the vehicle is moving, wherein the air injection pipe comprises a second end fluidly coupled to the exhaust tube and having an outlet positioned to provide air flow from the injection pipe into the exhaust tube upstream from the particulate filter. Passive soot regeneration with THC and CO reductions is realized by this introduced air flow.

A system for reducing emissions from an internal combustion engine includes a combustion chamber having an inlet and an outlet, a fuel delivery device for delivering fuel to the combustion chamber, and a control system for controlling a fuel to oxidizer ratio in the combustion chamber. A method of reducing emissions from an internal combustion engine includes the steps of: establishing a flow of oxygen-containing gas through a combustion chamber having an inlet and an outlet; introducing flow of fuel into the combustion chamber; igniting the fuel in the combustion chamber; operating an internal combustion engine to develop a stream of exhaust gas; introducing a flow of the exhaust gas into the combustion chamber; and controlling the flow of exhaust gas and the flow of fuel to minimize oxygen levels in exhaust gases downstream of the outlet.