Fuel EconomyRyan Ripp

CBE 5559/23/2008

Gasoline prices up 70% since January 2007 Decreasing dependence on foreign oil is a

national priority Global warming causing concern over CO2

emissions More fuel efficient vehicles helps with all

theses problems

Introduction

On average, cars purchased in 2006 had lower MPG ratings than in 1988◦ Fuel efficiency has decreased despite

improvements in engine efficiency◦ Due to higher sales of larger vehicles with more

powerful engines

Problematic Trend

Vehicles on roads in the United States

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 20100

20

40

60

80

100

120

140

160

Passenger Car

Other 2 axle-4 tire

Year

Mil

lio

ns o

f V

eh

icle

s

Driving force for fuel efficiency

Oil Prices over the last 60 Years

1940 1950 1960 1970 1980 1990 2000 2010$0

$20

$40

$60

$80

$100

$120

Year

Pri

ce f

or

a B

arr

el of

Oil in 2

008 D

ol-

lars

Low oil prices Consumer preferences and manufacturer

marketing Government indifference

◦ No new mileage standards passed from 1985 to 2007

Where is there room to improve fuel economy?

How did we get here?

It’s not just bigger vehicles getting bigger engines

Overpowered Cars

Which goes 0-60 faster?

1968 Chevy Corvette

2008 Ford Taurus

Tie: Both go from 0-60 in 6.5 Seconds

MPG vs HP

Car Model Combined MPG Horsepower 0-60 time (s)

Chevy Impala LS 47 211

  SS 40 303 6.4

Chevy Malibu LS 52 169 9.6*

  LTZ 43 252 6.6

Ford Taurus SEL  46 263 6.5

Ford Fusion S 54 160 8.1

Honda Accord LX 53 177 9.3

Honda Civic EX 61 140 9.4

  Hybrid 85 110 11.7

Toyota Camry LE 52 158 10.1

  XLE V6 47 268 6.2

Toyota Corolla CE 55 126 9.7

MPG vs HP

40 45 50 55 60 65100

150

200

250

300

350

Combined City and Highway MPG

Hors

epow

er

(hp)

Distance needed to go 0-60 with constant acceleration

d0-60 = vavgt0-60 vavg = 44 ft/s

Freeway onramp length: 1500 ft◦ (East Beltline Hwy from Gammon Road)

For d0-60 = 1500 ft, t0-60 = 34 seconds

How much power is enough?

Lower fuel consumption/CO2 emissions◦ Removing 1/3 of HP would cut petroleum use

enough to eliminate all oil imports from Middle East in ten years (TMQ)

Safer driving◦ Traffic deaths down 22% in March and 18% in

April◦ Drivers avoid maneuvers requiring quick

acceleration to save gas◦ Similar to how drivers of less powerful vehicles

are forced to drive◦ Corresponds to 8,000 fewer deaths per year

Benefits of Less Power

35 mpg standard by 2020◦ ~33% increase from old standard

Contains provision for automakersto be waived from standards◦ Big three automakers asking for waiver for 2015

interim standard◦ Also seeking $50 billion from government to try

and meet the new standards

Hyundai expects to meet 2020 standard by 2015

Government in action

Use smaller gasoline engines efficiently Electric motor operates car while idling or

during low energy output Gasoline engine and braking recharge

electric battery

Typically improve mileage 30%

Hybrids

Comparing Conventional Vehicles and Hybrids

10 20 30 40 50 60 700

100

200

300

400

500

600

700

800

900

Ford Escape

Cadillac Escalade

Honda Civic

Miles per Gallon

Gallons C

onsum

ed p

er

12,0

00 M

iles

Escalade hybrid costs ~$11,000 more◦ 15 mpg 20 mpg (Saves 200 gal/year)

Escape hybrid costs ~$9,000 more◦ 24 mpg 33 mpg (Saves 136 gal/year)

Civic hybrid costs ~ $8,000 more◦ 29 mpg 42 mpg (Saves 128 gal/year)

At current gas prices, buying a hybrid doesn’t pay off over the life of the vehicle

Most popular hybrids are from already fuel efficient models

Comparing Conventional Vehicles and Hybrids

Charge batteries from electrical grid Vehicle runs entirely on battery until charge

is gone, then operates as gas-electric hybrid Designed for commuting

◦ Able to drive 20-40 miles between overnight charges

Enabled by Lithium ion battery technology

Will be available in the near future

The Next Step: Plug-in Hybrids

Plug-in Hybrid Electric Vehicle (PHEV) available in 2009◦ Toyota Prius

Available as a PHEV in 2010◦ Chevrolet Volt◦ Saturn Vue◦ Volkswagon Golf

The Next Step: Plug-in Hybrids

Fossil fuels are still source of energy in most cases

Electrical energy is more efficient than internal combustion energy

~10-15% of energy from combustion reaches wheels of a car

Coal power plant is 40% efficient and electric motor is 85% efficient◦ 0.4 x 0.85 = 0.34◦ More than twice as efficient use of energy

Is it really more efficient?

How much does it cost to drive?◦ Toyota Prius requires 0.26 kWh to drive one mile◦ 1 kWh costs about $0.10 2.6 cents per mile◦ Gasoline hybrid Prius gets 55 mpg◦ ($3.65/gal) / 55 mpg = 6.6 cents per mile◦ Less than half the cost of operation

How much will these vehicles cost up front?

Is it really more efficient?

Carbon emissions◦ Gasoline: (0.75 g/mL)(3785 mL/gal)(mol CH2/14g)

= 200 mol CO2/gal (200 mol CO2/gal)/(55 mpg) = 3.6 mol CO2 per mile

◦ Coal: [(23 MJ/kg)(1 kg/0.9 kg CH)(1 kWh/3.6 MJ)]-1

x (1 mol CH/.013 kg CH) = 10.8 mol CO2 per kWh (10.8 mol CO2/kWh)(0.26 kWh/mile) = 2.8 mol CO2

per mile

◦ 22% reduction in CO2 emissions in the worst case

Is it really more efficient?

Technology is on the right track Need to get the technology to consumers

◦ Make more fuel efficient vehicles less expensive over the life of the car

Use hybrid technology in all types of vehicles

Reduce sales of vehicles that are too big and too powerful

Conclusions