..-.,more efficient than an advanced ICE, gasoline or diesel, at its best operating point, so the fuel
economy figures for hybrids are relatively similar whichever prime mover is used.CONCLUSIONS ABOUT PERFORMANCE AND PURCHASE PRICEDetailed analysis of potential improvements in fuel economy for a range of vehicle sizes
indicates that, in percentage terms, similar levels of increases can be expected for the different
vehicle sizes, if the same kind of efficiency improvements are added. Using a mid-size car as an
example, and holding its space, acceleration performance, and other comfort features constant at
1995 levels, it appears likely that a fuel efficiency level of about 53 mpg with a gasoline ICE, or
59 mpg with an advanced diesel engine can be attained in the year 2015 by using a combination of
advanced engine technology, improved materials and structural design, better aerodynamic design,
and improved tires. Such vehicles would cost $2,500 to $3,000 (in constant 1994 dollars) more
than a current mid-size vehicle. If very optimistic estimates are used for technology, an additional
10 mpg may be available, but costs may increase to over $6,000, largely owing to this
hypothetical vehicle’s carbon-fiber construction. OTA is somewhat skeptical that mass-produced
carbon-fiber auto bodies will be practical in this time frame.A mid-size electric vehicle would not have the same range capability but could be designed to
match a conventional mid-size vehicle’s performance and other attributes. Such a vehicle in
volume production could cost as little as $2,600 over the 53 mpg advanced conventional vehicle,
if powered by advanced lead acid batteries, and have a range of 80 miles. If nickel metal hydride
batteries can be produced cheaply ($180/kWh), an electric vehicle using them would be much
lighter, and have a range of 100 miles at about the same additional cost as a lead acid battery-
powered vehicle. Many observers believe that actual costs of the nickel metal hydride battery will
be twice as high as the most optimistic estimate, causing incremental vehicle price to about
$8,800. There is also the possibility of a 300-mile-range EV if lithium polymer batteries are
successfully manufactured, and such a mid-size EV could potentially be made for about $10,000
more than the 53 mpg advanced mid-size car. EV prices are quite sensitive to range or
performance assumptions, or both, so that relaxing the requirement to match conventional vehicle
performance characteristics can reduce EV prices. In particular, reducing range requirements will
sharply reduce EV prices.Hybrid vehicles offer the range of a conventional vehicle with potentially superior fuel economy
and the ability to operate as an electric vehicle with limited range. OTA chose to analyze only
autonomous hybrids--that is, vehicles that recharge their electrical storage systems through their
prime mover (engine, fuel cell), not from an external source (e.g., the utility grid). Autonomous
hybrids will be fuel efficient only if a good high-power storage medium (with specific power
>400 W/kg) is available that can be charged and discharged with high efficiency. No suchmedium exists now, but there are numerous potential candidates under development much as the
bipolar battery, ultracapacitor and flywheel. OTA’s analysis shows that a hybrid mid-size car with
basically the same performance capability as a current mid-size vehicle can attain about 65 mpg
using a battery, and about 72 mpg using an ultracapacitor or flywheel in 2015, using body
technology similar to the 2015 advanced conventional mid-size car. Cost is estimated at about
$3,200 over the 2015 advanced conventional vehicle, if a battery is used, and about $6,000 to