[blackjackel]

I ran an estimate of 1 MPG gain, and I calculated that it would take me 70 tank fillups to justify a $100 cost of lowering my car by two inches (springs).

If it saves just 2 MPG then the figure would half!

How much improvement in FE do you guys think I'll see by lowering my car?

Here's my math:

100 gallons x 1MPG saved = 100 miles (saved per 100 gallons spent)

100 miles (saved) / 42 (my current average MPG) = 2.38 (gallons saved per 100 gallons spent)

2.38 gallons (saved) x 4.5 (approximate current cost of gas) = $10.71 saved per 100 gallons

$100 (approx cost of lowering) / $10.71 ($ saved) = 9.337 (amount of times you need to save $10.71)

9.337 (amount of times) x 100 (gallons) = 933.7 (gallons before the mod pays for itself)

933.7 gallons / 13 gallons (current tank capacity) = 71.823 (tankfuls before the mod pays for itself)