What if the Prius Wasn't a Hybrid? What if the Corolla Were? An Analysis Based on Vehicle Limited Fuel Consumption and Powertrain and Braking Efficiency

The word hybrid has been synonymous with higher fuel economy. However, the standard measures of fuel economy in miles per gallon or fuel consumption in liters per 100 km are not able to describe whether any increase in fuel economy is due to the hybrid powertrain or due to other factors such as non-powertrain vehicle modifications. It would be beneficial to have a simple way to describe where the fuel economy benefit is coming from, either from vehicle related enhancements (non-powertrain) or powertrain related enhancements. In this paper, the simplified metrics of Vehicle Limited Fuel Consumption (VLFC) and Powertrain and Braking Efficiency (PABE) are developed. The metrics are then used to characterize hybrid and non-hybrid vehicles and deconvolve the contribution of hybrid and non-hybrid enhancements to vehicle fuel consumption. These metrics can be helpful for communicating to non-experts when examining cost/benefit ratios of potential actions to reduce fuel consumption.

EPA fuel consumption and road load data from hundreds of different 2009 models of cars and light trucks were analyzed using these new metrics. The sensitivity of vehicle limited fuel consumption and powertrain efficiency to parameters of mass and drivecycle are discussed for the hybrid and non-hybrid vehicles. The metrics are shown to provide an easy, plain-language way to describe several important factors related to fuel consumption.