TABLE 6-2 Fuel Consumption Reduction (percentage) by Application and Vehicle Type

Application

Engine

Aerodynamics

Rolling Resistance

Transmission and Driveline

Hybrids

Weight

Tractor trailer

20

11.5

11

7

10

1.25

Straight truck box

14

6

3

4

30

4

Straight truck bucket

11.2

0

2.4

3.2

40

3.2

Pickup truck (gasoline)

20a

3

2

7.5

18

1.75

Pickup truck (diesel)

23b

3

2

7.5

18

1.75

Refuse truck

14

0

1.5

4

35

1

Transit bus

14

0

1.5

4

35

1.25

Motor coach

20

8

3

4.5

NA

1.05

aCompared to a baseline gasoline engine.

bCompared to baseline diesel engine.

SOURCE: Adapted from TIAX (2009).

technologies in terms of fuel consumption reduction are as follows:

  • Hybridization

  • Replacement of gasoline engines with diesel engines

  • Improvement in diesel engine thermal efficiency

  • Improvement in gasoline engine thermal efficiency

  • Aerodynamics, especially on tractor-trailer applications

  • Reduced rolling resistance

  • Weight reduction

Costs, Cost-Benefit, and Implementation of These Technologies

The committee determined the direct costs of the technologies in several ways:

  • Estimates of presenters and manufacturers for the retail price equivalent (RPE), for the components and/or package.

  • Dealer’s data book list prices multiplied by 0.6 to estimate RPE.1

  • Complete vehicle cost premiums from various publications, such as for a hybrid bus.

In the following discussion and tables, the committee presents fuel consumption, in percent reduction, as a range or as one number representing its best estimate.2 Similarly, the capital costs are presented as a range or as one number representing the committee’s best estimate. The number for costs is then divided by the number for fuel consumption reduction (dollar cost/% fuel consumption reduction, $/%), and the result is called capital cost per percent reduction (CCPPR). Most of the focus is on the 2015 to 2020 time frame, but data are also presented for the 2013 to 2015 time frame. The applications discussed are tractor trailer, straight truck, pickup truck and van, refuse truck, transit bus, and motor coach. After considering these vehicle applications, alternative metrics for cost-benefit ratio are presented.

Tractor Trailer

This category of vehicles includes Class 8 tractors equipped with so-called fifth wheels for hitching to one or more trailers. The baseline vehicle for fuel consumption estimates is an older-generation aerodynamic tractor (drag coefficient, Cd = 0.63 to 0.64) with a sloped hood, roof fairings, aero bumpers, standard dual tires (coefficient of rolling resistance, Crr = 0.0068), standard 53-ft box van trailer, a diesel engine with peak thermal efficiency of 41 to 42 percent, and cycle thermal efficiency of 37 to 39 percent on a long-haul cycle with long periods of constant speed operation, camshaft-driven unit injection at 2,000 bar, variable geometry turbocharger, cooled exhaust gas recirculation (EGR), a diesel particulate filter (DPF) for particulate matter (PM) control, a cylinder pressure limit of 200 bar, and a 10-speed manual transmission with overdrive.


Engine (2015 to 2020). Improved thermal efficiency from 42 percent peak to 52.9 percent peak efficiency compared to the 2008 baseline, which represents a 20 percent reduction in fuel consumption. The baseline 2010 technology includes a DPF at a cost of $7,000 and a selective catalytic reduction (SCR) catalyst at a cost of $9,600. The 2015-2020 technology includes SCR with improved nitrogen oxides (NOx) conversion efficiency, a U.S. Environmental Protection Agency (EPA) required onboard diagnostic (OBD) system with closed loop controls, a high-pressure common rail fuel system with higher injection pressure of about 3,000 bar, piezo-electronic fuel injectors, increased cylinder pressure capability to 250 bar, and a bottoming cycle. The incremental cost is in the range of $23,000 in addition to the cost of 2010 emissions aftertreatment hardware. Besides the increase in

1

Personal communication from Dave Merrion to the committee, May 27, 2009.

2

The cost data are primarily from TIAX (2009) unless noted otherwise.



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