Experiece is 5pts Most nat gas fleet's that are operatng efficently do so today because they have lighter loads and shorter runs. Maintence costs run 800-1000 annual per truck higher than diesel. Shop upgrade is expensive and contingent to the jurisdiction of your local regs. and fire marshal. Low pressure fueling time averages about 45 minutes. High speed fueling options are expensive and complex, an there are few public options outside of private fueling centers.