The projections of fuel economy changes are quite sensitive to assumptions about future
gasoline prices. If fuel prices were twice the base-case levels, to $3.10 per gallon in 2015,
fleet fuel economy climbs to 39.0 mpg for cars and 28.5 mpg for light trucks, although one-
third of the difference in fuel economy over the base case is attributable to changes in sales mix. In
effect, of the 6 mpg difference for cars between the base case and the high fuel price scenario,
about 2 mpg is attributable to consumers switching to smaller cars. The differences between the
two scenarios are much smaller in 2005 owing to the reluctance of automakers to accelerate
model life cycles (which would cut profits) and limits on the rate that new technology can be
introduced.
Table 4-3 shows the approximate changes in drivetrain efficiency, weight, forces on the vehicle,
and fuel economy of a “best-in-class” mid-size car in 2015. This car is projected to attain a 25
percent reduction in fuel consumption, or a 33 percent increase in fuel economy, which is about 9
percent better than the average increase for the fleet.The changes relative to current 1995 cars and light trucks are easier to understand in a
qualitative form. The vehicles in each size class will be somewhat roomier, and their bodies will be
stronger and more rigid. Along with other safety improvements such as dual air bags, side impact
restraints, roof crush strength improvements, antilock braking system, and traction control, these
improvements imply that the vehicles will be much safer than today’s vehicle, if driven in similar
conditions. Engines will be much smaller in displacement (by 20 to 30 percent), and most of these
cars will feature variable valve timing, although only about 35 to 40 percent of light trucks will
have this technology. However, the smaller engines will produce nearly equal torque and 20
percent more power (at high rpm) relative to today’s engines, so that maximum performance will
be actually enhanced, with some loss in “elasticity,” or the ability to accelerate without shifting
gears. The use of five-speed automatic transmissions and even some continuously variable
transmissions should, however, make the loss almost invisible to most drivers. In other words, the
2015 cars will be better in most respects such as roominess, safety, performance, and fuel
economy relative to current cars, and their emissions will meet the California-mandated
LEV standards. Hence, the cost increases need not be justified on the basis of fuel savings alone,
but also on the basis of perceived and real quality improvements.
ADVANCED CONVENTIONAL VEHICLES
The baseline projection suggests that considerable technological improvements will occur in all
cars even in the absence of any intervention in market forces. This section characterizes the
maximum potential of conventional technology in 2005 and 2015, using the technology benefits
described in the sections on individual technologies.
Attaining these high levels of technology would require some form of intervention in the
market to become a reality. In this context, we have constructed two scenarios for each date,
one using the mean or manufacturers’ average estimate (designated as “m”) of technology benefit,
and the second using the most optimistic benefit estimates (designated “o”) obtained from the
auto manufacturers (virtually all of the data on conventional technologies was obtained from auto
manufacturers).