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!

[impala454]

That spreadsheet is very admirable, but I'd seriously doubt the average joe keeps something so detailed. Not to mention have a similiar spreadsheet about the car they would be purchasing to compare with. Besides, what is the real difference in maintinence between any two given vehicles?

All this is is to help answer the simple question people keep asking: "Can I garage my current vehicle, purchase a better gas mileage vehicle, and have it pay for itself in gas savings?"

[Dogmeat]

That spreadsheet is very admirable, but I'd seriously doubt the average joe keeps something so detailed. Not to mention have a similiar spreadsheet about the car they would be purchasing to compare with. Besides, what is the real difference in maintinence between any two given vehicles?

All this is is to help answer the simple question people keep asking: "Can I garage my current vehicle, purchase a better gas mileage vehicle, and have it pay for itself in gas savings?"

Depends, what kind of vehicle, and how well does the owner maintain it? You start to see that once a vehicle gets more miles on it the better the owner has maintained it over the course of it's life, the less it costs them to own as it gains miles ... somone who never changed the oil, never kept it clean, never did anything to maintain it, the vehicle will develop more problems over the years.

Somone who drove the crap out of their vehicle, obviously, will have more costs associated with maintenence than somone who is a conservative driver.

Or you could own a Ford ....