Fleet fuel economy measures the average miles per gallon (MPG) across all vehicles in a fleet operation. For diesel fleets, even small improvements compound dramatically — a 5% MPG improvement on a 50-truck fleet spending $200,000/month on fuel saves $10,000/month or $120,000/year. Combustion catalyst additives like Fuel Ox deliver 2-8% fuel economy improvements by optimizing the combustion process itself.