Gas mileage formula Options

[impala454]

So I was reading on some site the other day, some dude had done some calculations for himself and figured out that his break even point for parking his current vehicle and getting a high mpg car for daily driving was at around $5.00/gallon. Made me curious, I calculated it for myself, then figured I could just make an easy to use equation for everyone else. So I broke out the rusty old algebra and came up with this. Someone can correct me if I'm wrong as it was a few lines worth of solving to make it simpler:

P = GX(1/Y - 1/Z)

where:
X = number of miles per month you drive
Y = mpg of current vehicle
Z = mpg of proposed vehicle
G = gas price in $ per gallon
P = monthly payment for new vehicle (don't forget insurance )

So you can plug in numbers wherever you want and figure it out for yourself. Also keep in mind this assumes either that your current vehicle is paid off, or that you will keep the vehicle and its current payments (effectively cancelling each other out). So to figure out my own gas price break even point (assuming $300/mo for a 35mpg honda civic):

G = P/X(1/Y - 1/Z)

G = 300 / 2100(1/17 - 1/35) = $4.722/gallon

or say at the current gas prices, what payment on a new 35mpg vehicle would break me even?

P = GX(1/Y - 1/Z)

P = 3.50 2100 (1/17 - 1/35) = $222/month

So I guess I'll be keepin the gas hog a while longer . I could prob go find a used civic or somethin, but I just don't dig buying a used vehicle from someone I don't know. Anyhow, lets see what everyone else's is!

[chook]

I got an 02 civic ex for 76000 last year. What that stupid formula doesn't account is the total cost of vehicle over its lifetime. Stupid formulas like this is how dogmeat says an H3 is cheaper than a prius.