Advanced Automotive Technology: Visions of a Super-Efficient Family Car

strategy where the engine is on all the time; however, emissions and drivability for the type

2 hybrid should be much easier to perfect. The type 2 hybrid may make more sense if

simplicity, reliability, and low cost are more important than attaining maximum fuel

economy.

The percentage changes in fuel economy should be generally applicable to all size classes

examined, given the inaccuracies inherent in our simple methodology. Available data from existing

simulations provided by Chrysler^66 are consistent with the estimates provided above.

Data from parallel hybrid vehicles in the most recent “HEV challenge” were also examined. It is
interesting to note that the winning cars in this event have almost always used a parallel design,
and series hybrids have fared poorly. The University of California at Davis achieved the best fuel
economy (by far) in the road rally segment. Its vehicle used only 0.45 gallons of gasoline and
8.51 kwh of electricity to cover 134.86 km^67 --a “gasoline equivalent” fuel economy of 69.32
mpg if the electricity generation efficiency is about 34 percent. Although this is an impressive
attainment for a student competition, this is not a uniquely high fuel economy (several
conventional vehicles attain equivalent fuel economy on the EPA highway test), and the vehicle
itself is limited in its capabilities. The vehicle is basically an EV with a small engine that is
started only when the battery is discharged by over 50 percent or when the vehicle is traveling
faster than 70 mph. Range as a pure EV is 60 miles, and about 180 miles as a hybrid with
available battery power; after 180 miles, the battery must be recharged or the vehicle can limp
home powered only by the engine, which produces 15 kW (20 hp). Although the vehicle’s total
power output with fully charged battery and engine available is 60 kW (which provides almost
exactly 50 kW/ton of peak power for acceleration^68 ), the power drops off once the battery is
depleted to 50 percent DoD. Hence, vehicles such at the UCDavis hybrid demonstrate that
high levels of fuel economy can be obtained while overcoming some of the range limitations
of pure EVs--but these vehicles are far from the “full capability” hybrids that OTA
examines in this report.

Prices

Prices for the series and parallel hybrids were computed

employed for EVs. Battery costs and motor costs are

estimates. The generator is assumed to be less expensive

using a methodology similar to the one

identical to those used for EV cost

than the motor owing to its restricted

speed range, and we have estimated costs at $25/kWh (peak). Ultracapacitor and flywheel costs

are as outlined in chapter 3 and are DOE goals rather than real cost estimates. Investments were

estimated at $200 million (incremental) for an HEV facility designed to produce 100,000

vehicles/year.

(^66) Chrysler, presentation to OTA, September 8, 1994.
(^67) E. Chattot et al., "The Continuing Development of a Charge Depletion HEV, Aftershock, at UC-Davis”, SAE Paper 95000.
(^68) Actually, a parallel hybrid will require greater 50 kW/ton of available peak power to match OTA’s power requirement, because part of the
power for peak acceleration is provided by the vehicle’s electric motor, at 50 kW/ton required and part by the engine, at 60 kW/ton required.