The Influence of Weight

•Freight-ton miles per heavy-duty diesel truck

•Average model weight of light-duty gas vehicles and trucks

By Natalie Zaczek

Freight-Ton Miles

Freight Miles Driven

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

Year

1 T

on

* 1

Mil

lio

n M

iles

Diesels Freight Miles

• Amount of freight being transported has increased steadily every year•There is an increasing demand for freight transportation•The plateau in total freight, but increase in freight-miles means that less freight per haul. (There is a steady increase of length of haul, so there is not a decrease in the distance freight travels)

Total Freight

0

500

1000

1500

2000

2500

3000

1965 1970 1975 1980 1985 1990 1995 2000 2005

YearM

illi

on

s o

f T

on

s

Diesel

Freight/PersonFreight/Person

77.5

88.5

99.510

1960 1970 1980 1990 2000 2010

Year

Frei

ght(

tons

)/Per

son

Diesels

Freight/Vehicle

250

300

350

400

450

500

1960 1970 1980 1990 2000 2010

Year

Fre

igh

t (t

on

s)/

Die

sel

Tru

ck

Diesels

Freight/Vehicle

• There was a dramatic increase from 1980-mid1990s

• Peak in mid-1990’s• Decreases from mid-1990’s-

2001

• There was a rapid decrease until 1980 (when the freight/person was flat)

• Peak mid-1990s• Decreases from mid-1990’s-2001

Light-Duty Gas Weight Trends for the Model Year

-Vehicles and trucks weighed the same in 1975-Rapid decline in weight from 1975-1980-Weights constant from 1980-1990s-Weight increase from the 1990s to current

Average Weight of Light-duty Gas Vehicles and Trucks

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1970 1980 1990 2000 2010

Model Year

We

igh

t (l

bs

)

Light-duty Gas Vehicles Light-Duty Gas Trucks

FUEL ECONOMY OF U.S. VEHICLES BY MODEL YEAR

FIGURE 1

SOURCE: EPA

•1975-1980 a rapid increase in fuel economy and a rapid decline in weight

•1980-2002 a slight decrease in fuel economy and a large increase in weight

Weight Increase and Decrease

• Influence on weight decrease (1975-late 1980’s)

– CAFÉ• Govt. policy to increase fuel efficiency in 1975

– FMVSS • no safety changes from 1974 -1986

• Influence on weight increase (late 1980’s – 2004)

– FMVSS • Increase in weight of safety equipment

– Technology • Used to increase weight and acceleration

FMVSSFederal Motor Vehicle Safety Standards

• Federal Motor Vehicle Safety Standards (FMVSS) – Reverse engineering to find out how much weight was going towards

safety– Safety includes avoiding crashes, fires, and other hazards, and

regulating crashes.– Weight in passenger cars changed little from 1974-1986 because no

new FMVSS changes– Many safety technologies in cars later than in light trucks– There is an increase in safety weight from 1990-2000 and there is

also an increase in the average weight per model year during the same time

Average weight of required saftey equipment for both Light-duty gas vehicles and trucks

020406080

100120140

1970 1980 1990 2000 2010

Year of implementation

Wei

gh

t in

lb

s o

f F

MV

SS

ad

dit

ion

Light-duty GasVehicles

Light-duty Gas Trucks

Average Weight of Light-duty Gas Vehicles and Trucks

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1970 1975 1980 1985 1990 1995 2000 2005 2010

Model Year

Wei

gh

t (l

bs)

Light-duty Gas Vehicles Light-Duty Gas Trucks

Technology Improvement = Weight Gain

•Technology goes to increase weight and acceleration, not fuel economy

•Weight increased 21%

• Horsepower increased

79%

AVERAGE U.S. VEHICLE CHARACTERISTICS: 1981 TO 2000

FIGURE 2

SOURCE: EPA

Ton-mpg

– Ton-MPG is the miles per gallon times the weight in tons (fuel economy)

– Tells ability to move weight

– Also tells about the power train and drive-line efficiency

Average Ton-MPG

0

5

10

15

20

25

30

35

40

45

1970 1975 1980 1985 1990 1995 2000 2005

Year

Light-Duty Gas Vehicles Light-Duty Gas Trucks

Average Ton-MPG per Model Year

05

101520253035404550

1970 1975 1980 1985 1990 1995 2000 2005 2010

Model Year

Av

era

ge

To

n-m

pg

fo

r a

ll w

eig

hts

Light-duty Gas Vehicles Light-Duty Gas Trucks

Why did the ton-mpg increase while the weight increased?

• There are many factors that affect fuel economy:– Weight– Technology

Average Ton-MPG

0

5

10

15

20

25

30

35

40

45

1970 1975 1980 1985 1990 1995 2000 2005

Year

Light-Duty Gas Vehicles Light-Duty Gas Trucks

If the 2000 model year light vehicle had the same performance and weight as the 1981 model year, there would have been a 25% higher fuel efficiency.

Average Weight of Light-duty Gas Vehicles and Trucks

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1970 1975 1980 1985 1990 1995 2000 2005 2010

Model Year

Weig

ht

(lb

s)

Light-duty Gas Vehicles Light-Duty Gas Trucks

Conclusions on Weight

• Weight affects fuel economy

• More freight is being circulated via trucks in 2002 compared to 1975. This means that more weight is being transported.

• Weight declined, but then start to increase again all while the fuel economy also increased. This indicates that there are other factors involved in the fuel efficiency such as technology.

• Once technology has reached a plateau, changes in weight may affect changes in fuel economy more.