A pintle-regulated Venturi (PRV) is a patented fuel-air induction to improve the performance of spark-ignited automotive engines system (U.S. patent 6,868,830). PRV uses a convergent-divergent nozzle to significantly recover the pressure drop across the pintle body and maintain a higher engine intake manifold pressure to boost engine torque. With a higher engine torque using the same amount of fuel, the fuel economy will be increased significantly. On the contrary, a conventional throttle plate causes unrecoverable pressure loss, reducing engine torque and efficiency. Specifically, engine torque is increased and fuel economy is improved while exhaust pollutants and greenhouse gases are significantly reduced by exchanging a conventional intake manifold with a pintle-regulated Venturi (PRV) induction system on a conventional spark-ignited engine. A schematic comparison of the two induction systems is shown below.