with a fuel efficiency of almost 55 mpg^13 (European 1/3 mix cycle) on a car of weight similar
to that estimated for the hypothetical Taurus in 2015. If the DISC engine turns out to be as
efficient as the DI diesel (as is widely expected), the estimates of 53.2 and 59.0 mpg seem quite
reasonable and possibly conservative. Costs and fuel economy for all four classes of vehicles
examined in all scenarios are shown in table 4-5.
An important point to note is that these hypothetical maximum scenarios hold size,
performance, and (implicitly) vehicle features constant over time--that is, the 2005 and 2015
Taurus vehicles are identical in size, performance, and features to the 1995 Taurus. However,
OTA expects size, performance, body rigidity, and other features to increase over time;
consequently, except for their higher fuel economy, vehicles in these scenarios are less desirable
than the ones in the baseline. Changing the attributes of body rigidity, size, and performance to
levels equivalent to those defined under the “baseline” scenario will reduce fuel economy by 6 to 7
percent from the values shown in table 4-5. In other words, the advanced 2015 Taurus would
obtain a fuel economy of about 50 (DISC) to 55 (DI diesel) mpg, if its performance and
other features matched the 2015 Taurus baseline.
The emissions of these advanced technology vehicles are expected to meet California LEV
levels. In 2005, the engine technology forecast is quite similar to the “baseline scenario”
technology forecast for 2015, and smaller displacement engines with VVT on light-weight cars
(relative to the baseline) actually have an advantage in meeting LEV standards. The 2015 scenario
assumes that DISC engines and the diesel can meet LEV standards through the use of a lean NOX
catalyst. Because direct injection engines, both diesel and gasoline, have lower cold start and
acceleration enrichment related emissions than conventional gasoline engines, their overall impact
on in-use emissions is expected to be positive.
ELECTRIC VEHICLES
EVs substitute a battery (or other device capable of storing electricity in some form) and
electric motor for the gas tank/ICE/transmission components of a conventional vehicle. As
discussed earlier, the key drawback of EVs has been the inability of batteries to store sufficient
energy to allow a large enough range capability.
Although batteries can store only a small fraction of the energy in the same weight and volume
of gasoline, EVs may gain back some of this disadvantage because of several efficiency
advantages. First, conventional ICE vehicles use about 10.8 percent of their fuel during braking
and at idle when the engine contributes no useful work; electric motors need not work during EV
braking and idling. Second, most of the accessories used in an ICE-powered car, such as the
water pump, oil pump, cooling fan, and alternator can be eliminated if battery heat losses are not
high, as motor and electronics cooling requirements do not require much power. In addition, the
hydraulic power steering in a conventional vehicle must be replaced by electric power steering,
which consumes only a fraction of the power of conventional systems.^14 The reduction in