In Colorado and other high altitude areas, the motor vehicle plays a disproportionate and adverse role in atmospheric pollution due to fuel enrichment and other inherent factors associated with engine operation in these areas. As a consequence, a sizeable program is required, not only for emission reduction in elevated areas, but for fuel economy improvement as well. The report deals with the devices, which include certain parametric adjustments to help compensate for the high altitude effect on carburetion and combustion in the conventional automobile engine.