Just for fun I used the number in this thread to calculate the time it would take to make up the cost of the mod. It came out to 2.06 years.

current mpg 15
yearly mileage 34944
gallons per year 2329.6
cost per gallon $2.50
cost per year $5,824.00

cost of mod $2,000
New Mileage 18
Gallons per year 1941.3333
Cost per year $4,853.33
Savings per year $970.67
years to pay off mod 2.0604396

 

while the number crunching is fun it is also 'assuming' 18 MPG with the mods. What about if he only gets 17 or 16. It'd be interesting to see those numbers as well.

 

Good point.

At 17mpg it came to 2.9 years and at 16mpg its 5.5 years.

17MPG
current mpg 15
yearly mileage 34944
gallons per year 2329.6
cost per gallon $2.50
cost per year $5,824.00

cost of mod $2,000
New Mileage 17
Gallons per year 2055.5294
Cost per year $5,138.82
Savings $685.18
years to pay off mod 2.918956

16MPG
current mpg 15
yearly mileage 34944
gallons per year 2329.6
cost per gallon $2.50
cost per year $5,824.00

cost of mod $2,000
New Mileage 16
Gallons per year 2184
Cost per year $5,460.00
Savings $364.00
years to pay off mod 5.4945055


This of course is all based on the numbers int he thread with a bit of assumption. For example the miles per year were based on 6 days a week driving his commute of 112 miles round trip.