How much more MPG would you get lowering your car 2 inches?
 

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)

how about this lower your car for looks then the change for mpg wont matter as much :)

my civic has struts and springs and they allow me to corner faster which really helps my EOC on certain parts of my commute.

Btw you also should include the cost of a re-alignment If you decide to mess with your car's suspension.

re-alignment?

blackjackel -

Because someone will be disassembling the suspension to install the shorter springs, you will need to get the wheels realigned :

Wheel alignment - Wikipedia, the free encyclopedia

You estimated $100 for the installation. If your estimate doesn't include alignment, you may need to increase the installation estimate to anywhere from $150 to $180 total.

CarloSW2

Nevertheless, he has a valid question. Does anyone have any numbers before/after lowering?

Ivan: not that I'm aware of.

Also, the in/effectiveness of lowering will vary from car to car as well.

blackjackel: you should add your vehicle to the garage so everyone knows what kind you're referring to in all your posts (it'll appear under your username).

Alignment is free.
Pelican Technical Article: Home Alignment

I lowered my truck 3" in front and 6" in back. In addition I went to smaller tires up front to get another inch.

My truck went from 76" tall to 72" tall and I gained 1.0 MPG.

The truck also corners much better.

I didn't notice anything upon my own experiments. Handling, maybe looks...