Monday, April 27, 2009

Cash for Clunkers and the GPM Calculator

The GPM calculator has now been updated with all MPG levels from 10 to 30 MPG (and all even MPG values from 30 to 50 MPG).

This tool is ideal for letting you see your gas and cost savings from a "Cash for Clunkers" trade in.

How to use it: Select a driving distance and gas price of your choice. Compare your current MPG level (15 MPG) to a wide range of more efficient MPG levels (e.g., 24 MPG, 27 MPG, 33 MPG) to see your gas and cost savings.

You might also find the following tables helpful:

1) These tables directly caclulate the gas and cost savings of trading in a car that gets 18 MPG or less for different combinations of cars with higher MPG.

2) The following table shows why MPG is misleading as a measure of gas savings and why we need to look at "GPM" measures such as "Gallons per 100 Miles". "Gallons per 100 miles" makes clear that the improvement from 14 MPG to 25 MPG saves more gas (3 gallons per 100 miles) than any possible improvement on a 33 MPG car.
Here is a downloadable version of the table below.





MPG

Gallons per 100 Miles

Gas Costs to Drive 10,000 Miles

10

10.0

$2,500

11

9.1

$2,273

12

8.3

$2,083

13

7.7

$1,923

14

7.1

$1,786

15

6.7

$1,667

16

6.3

$1,563

17

5.9

$1,471

18

5.6

$1,389

19

5.3

$1,316

20

5.0

$1,250

21

4.8

$1,190

22

4.5

$1,136

23

4.3

$1,087

24

4.2

$1,042

25

4.0

$1,000

26

3.8

$962

27

3.7

$926

28

3.6

$893

29

3.4

$862

30

3.3

$833

31

3.2

$806

32

3.1

$781

33

3.0

$758

34

2.9

$735

35

2.9

$714

36

2.8

$694

37

2.7

$676

38

2.6

$658

39

2.6

$641

40

2.5

$625

41

2.4

$610

42

2.4

$595

43

2.3

$581

44

2.3

$568

45

2.2

$556

46

2.2

$543

47

2.1

$532

48

2.1

$521

49

2.0

$510

50

2.0

$500



If you want to know your carbon impact, saving 100 gallons of gas reduces carbon dioxide emissions by roughly 1 ton.

[Update June 20: Here is a link to the final June 18 plan.]