MPG Gain -- Time to pay off

[Noel]

I have a spreadsheet that has price per gallon/mpg figured out already so that I can figure out how long the payback is on any modification.

This is based on a $3.50 per gallon gas price.




MPG | Price per mile | Amount saved per mile per 1 mpg gain

70 $0.0500 0.000725
69 $0.0507 0.000746
68 $0.0515 0.000768
67 $0.0522 0.000791
66 $0.0530 0.000816
65 $0.0538 0.000841
64 $0.0547 0.000868
63 $0.0556 0.000896
62 $0.0565 0.000925
61 $0.0574 0.000956
60 $0.0583 0.000989
59 $0.0593 0.001023
58 $0.0603 0.001059
57 $0.0614 0.001096
56 $0.0625 0.001136
55 $0.0636 0.001178
54 $0.0648 0.001223
53 $0.0660 0.001270
52 $0.0673 0.001320
51 $0.0686 0.001373
50 $0.0700 0.001429
49 $0.0714 0.001488
48 $0.0729 0.001551
47 $0.0745 0.001619
46 $0.0761 0.001691
45 $0.0778 0.001768
44 $0.0795 0.001850
43 $0.0814 0.001938
42 $0.0833 0.002033
41 $0.0854 0.002134
40 $0.0875 0.002244
39 $0.0897 0.002362
38 $0.0921 0.002489
37 $0.0946 0.002628
36 $0.0972 0.002778
35 $0.1000 0.002941
34 $0.1029 0.003119
33 $0.1061 0.003314
32 $0.1094 0.003528
31 $0.1129 0.003763
30 $0.1167 0.004023
29 $0.1207 0.004310
28 $0.1250 0.004630
27 $0.1296 0.004986
26 $0.1346 0.005385
25 $0.1400 0.005833
24 $0.1458 0.006341
23 $0.1522 0.006917
22 $0.1591 0.007576
21 $0.1667 0.008333
20 $0.1750 0.009211
19 $0.1842 0.010234
18 $0.1944 0.011438
17 $0.2059 0.012868
16 $0.2188 0.014583
15 $0.2333 0.016667
14 $0.2500 0.019231
13 $0.2692 0.022436
12 $0.2917 0.026515
11 $0.3182 0.031818
10 $0.3500

[Tourigjm]

you lost me...

:blink:

[Noel]

It's handy for me to be able to just see a price per mile at certain mpg...

That's all it is, saves you 30 seconds of math.


Like the moonies...... looked at the mpg gain they could give, checked to see how long the payback was,,,, at almost a year for me, they fall pretty low on the mod list.

[groar]

Originally Posted by Tourigjm

you lost me...

As said in several other threads, it is difficult to know how much you have saved when you get from n MPG to n+1 MPG. This is why some people are suggesting to use GPM (Gallon Per Mile) as European are using LHK (Liter per Hundred Kilometer).

Real example : one year ago I was at 7.0l/100 (33.6MPG) and I'm now at 5.9l/100 (39.8MPG). I'm driving 39.8-33.6=6.2 more Miles Per Gallon, which is a 18.5% improvement. In this case with my 14.3G tank I drove 14.3*6.2=88.7 more Miles.

But if I want to know how much petrol, CO2, money... I saved, I have to use the other way : I consumed 7.0-5.9=1.1 less Liter per 100kms, which is a 15.7% saving. I just have to multiply by cost of petrol and I know my money saving : 1.1*1.4€/l=1.54€/100kms, ie 0.924€/day (60kms/day).

This sheet can be applied to your modding. If you win 2 MPG from 33 to 35, then you see how much you save per Mile : 0.003314 + 0.003119 = 0.006433$/M. If you drive 40 Miles/day then you save 0.25732$/day. If your mod costs 100$ then it will pay for itself after 100 / 0.25732 = 389 days.

Hope it helps,

Denis.