Fifteen percent saving results on improvements based on 100,000 miles per year. This does not take into consideration a percentage of better engine longevity and downtime costs.

How about adding $3,000 to each $ savings for less oil changes, engine longevity AND overhaul DOWNTIME?

If you notice, -the 5 MPG Fuel Hog's owner will recover the investment 40% faster than the fuel-efficient aero's 15% improvement. If U drive 125k/year multiply the $ savings times 1.25 (150k = x1.5; 175k = 1.75 etc.)

MPG
Gallons
Price
Total
% Savings
Savings
5
20k
$3.00
$60k
15%
$9k
"
"
$3.25
$65k
15%
$9.75k
"
"
$3.50
$70k
15%
$10.5k
5.5
18,182
$3.00
$54,545
15%
$8,182
"
"
$3.25
$59,091
15%
$8,864
"
"
$3.50
$63,637
15%
$9,546
6
16,667
$3.00
$50k
15%
$7,500
"
"
$3.25
$54,168
15%
$8,125
"
"
$3.50
$58,334
15%
$8,750
6.5
15,385
$3.00
$46,154
15%
$6,923
"
"
$3.25
$50,001
15%
$7,500
"
"
$3.50
$53,847
15%
$8,077
7
14,286
$3.00
$45,857
15%
$6,429
"
"
$3.25
$46,430
15%
$6,964
"
"
$3.50
$50,001
15%
$7,500
7.5
13,333
$3.00
$40k
15%
$6k
"
"
$3.25
$43,332
15%
$6,500
"
"
$3.50
$46,666
15%
$7k
8
12,500
$3.00
$37.5k
15%
$5,625
"
"
$3.25
$40,625
15%
$6,094
"
"
$3.50
$43,750
15%
$6,563
Based on 100,000 miles per year TruckingInOverdrive.com