—.,.Many of the available advanced technologies are relatively cost-effective, and design and
technology changes to reduce aerodynamic drag, tire rolling resistance, engine friction, and
transmission loss are expected to be adopted even in the baseline scenario, although the
reductions are not as large as those postulated in this maximum scenario. Other technologies such
as four-valves/cylinder, variable valve timing, advanced fuel injection, and variable-tuned intake
manifolds are likely to be adopted for reasons of performance, drivability, and low emissions
potential, although the market penetrations of these technologies are expected to grow slowly
over the next two decades. This section examines the fuel economy potential of a hypothetical
“best-in-class” car, if all technologies that are fully developed and available for
commercialization are adopted in such a way as to maximize fuel economy, while keeping
interior volume and performance constant at 1995 levels.
Because this analysis is not based on costs, cost-effectiveness, or on vehicle life-cycle
considerations, the best-in-class vehicle in all four market classes uses the same set of
technologies with only a few exceptions (as discussed below). Hence, focusing in on one market
class and describing the changes in detail provides a comprehensive picture of the changes to all
classes considered. The intermediate car class is selected for this description, and the most
popular car in this class, the Ford Taurus, is the 1995 benchmark, or reference, vehicle. The
current vehicle has an interior volume of 100 cu ft and trunk volume of 18 cu ft. It is powered by
an overhead valve (OHV) two-valve V-6 that produces 140 horsepower, and has a peak torque of
165 ft. lb @ 3,250 rpm. It uses a four-speed automatic transmission with lockup torque converter,
an axle ratio of 3.37, and a relatively steep overdrive ratio of 0.67. The Taurus weighs 3,130 lbs
and is tested at 3,500-lb inertia weight. Its composite fuel economy is 28.0 mpg, which is 1.5 to 2
mpg higher than many other competitors in its class. Its performance is characterized by its O to
60 mph time of about 10.4 seconds (based on car enthusiast magazine tests). The Taurus has a
remarkably high ratio of highway to city fuel economy of about 1.69, probably as a result of its
low numerical overdrive ratio. This number is usually closer to 1.5 in most cars.Table 4-4 traces the hypothetical evolution of a mid-size car equivalent to the Taurus under the
two scenarios for 2005 and 2015. The greatest difference between the baseline and the advanced
technology scenarios is in material substitution and the resultant weight. Four weight-reduction
scenarios were considered for this analysis. The assumptions involved in each case are described
in more detail in box 4-1, along with the approximate material compositions of the vehicles.^11 The
2005(m) vehicle is made of steel, but substantial weight has been removed by optimizing the
design and using an aluminum engine. It weighs 15 percent less than the current Taurus. The
2005(0) vehicle uses considerable aluminum in the body as well, but the design does not take full
advantage of aluminum’s properties and achieves only a 20 percent weight reduction. For 2015,
the (m) vehicle’s aluminum body is optimized and attains a 30 percent weight savings, whereas the
(o) vehicle has a carbon fiber composite structure yielding a 40 percent weight reduction from the
current Taurus. The costs of these material changes range from modest ($200 to $400) for the
steel redesign and aluminum engine to high ($2,000 to $8,000) for the carbon fiber Taurus.(^11) Energy and Environmental Analysis, Inc.,“Domestic Manufacturers Light Duty Truck Fuel Economy Potential to 2005,” prepared for Martin
Marietta Energy Systems, January 1994.