EPA’s estimate of average fuel economy trends for the past 25 years. One might expect a continued gradual decline with no changes to CAFÉ or the fuel price market. The U.S. EPA’s report also shows the variation between models sold in 1999. As shown in Figure 5-2, most passenger cars are estimated to achieve between 22 and 36 mpg, with a small percentage achieving more or less than this range. Similarly, over 80% of light trucks achieve between 15 and 23 miles per gallon, with most of the rest achieving up to 32 mpg. This sales fraction data is useful in determining the possible shifts in fuel economy trends.
The comparison of fuel cycle emissions is intended to represent a significant volume of vehicles that could be certified as PZEVs. These PZEV vehicles could displace battery ZEVs so the types of vehicles represented in this study are intended to be a consistent type of vehicle. These comparisons would then represent vehicles in similar classes and performance capabilities. This is not necessarily straightforward, as various vehicles have different attributes that are particular to the technology and cannot be replicated in another vehicle technology. This will be discussed further in the following subsections.
Figure 5-1. Fuel Economy Trends, 1999
Source: U.S. EPA 19
Figure 5-2. Sales Fractions of 1999 Passenger Cars and Light Duty Trucks by Fuel Economy