GPHM Table to see Gas Savings on Trade Ins (Including Cash for Clunkers)

[Update June 10: There are two personal benefits from Cash for Clunkers. One is the voucher. That one's clear. But the other benefit is the dollar value of the gas savings that result from a trade in. That one is less obvious because gas savings are a not a one-to-one function of MPG increases.

In many cases--especially for very inefficient cars--the savings in gas costs will be larger than the rebate. In that sense, the gas savings can be thought of as a kind of "matching" program for the voucher. It doubles the value of the voucher.]

The table below shows how different levels of Miles per Gallon (MPG) translate to Gallons per Hundred Miles (GPHM). You can easily calculate the gas savings from a trade in by subtracting the new GPHM from the old one. For example, trading in a 17 MPG car for a 28 MPG car saves 5.9 minus 3.6 = 2.3 gallons per hundred miles. That saves more than 200 gallons of gas (and $500) over 10,000 miles of driving. It also saves 2 tons of CO2 emissions over that distance. The gas cost calculations below assume that gas costs $2.50 per gallon.

Here is a downloadable version of the table below.

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.

Finally, this online calculator will let you compare gas consumption and gas costs for any combination of MPG, driving distance, and gas price. It also allows you to calculate gas consumption and cost information on 2009 cars.

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