How about how to compare the costs of buying a cheap car vs. Uber, bus, etc. Just a simple comparison list? Over what time period? If I look at one year, for instance, the car will obviously be the most expensive by far because of the purchase price not being amortized for long
I'd pick a per-month time period; I don't see any reason to pick something arbitrary like "six months."
Estimation of Car:
- Purchase price. Assuming you are buying it with cash, amortize the purchase price over the expected life span of the car. If you buy a $10,000 car and expect it to last 10 years, that's about $83/month. If financing, use the monthly payment.
- Insurance. Mine costs about $45/mo for one car.
- Mileage. I know people have all sorts of opinions, but I like to use the IRS mileage estimate for gas + wear and tear for the sake of simplicity. If you generally put 100 miles on your second car per month, multiply that by $0.54, for about $54 in gas and wear and tear monthly.
Estimation of "Make Do": This is trickier, because you have to run a few comparisons based on what you are actually likely to use or need. I don't think you need a zipcar membership
and a bus pass
and ubers; that seems like overkill. I would probably use the bus/walking/bike as my base "getting around" option, and pick either ubers or zipcar as my backup method of transportation. Uber has the benefit of not having a base monthly fee to use, zipcar has the benefit of being easier if you need to run lengthy errands, or haul people or stuff.
Try to write down every trip you remember taking in the second car the last week you used it, and extrapolate it to try to estimate the trips you take in a typical month. What happens with those drives? Does your younger daughter need a booster seat? Do you take shopping trips where you haul back a lot of groceries/go to Home Depot to pick up bulky items? Could you adjust your schedule so you do those big trips on weekends or evenings? Do bus routes take you to your most common locations? Would you go on enough bus trips to justify a monthly pass (instead of paying a couple of dollars for individual rides - in my city, bus passes are pricey enough that they aren't worth it unless you're taking the bus nearly every weekday)? You need these details to figure out a good estimate.
In my personal situation, I can walk for groceries, bike to work, bus many close places, and unusual places it's easiest to get an uber. I'd estimate 10 bus trips a month at $1.50 each for $15, and liberally estimate 4 uber rides at $25 each, for $100. So, I'd guess $115/mo. Let's say your car fits the parameters I've outlined above ($83/mo purchase price, $45/mo insurance, $54/mo mileage, for a total of $182/mo) - it'd be financially worth it for me to ditch the car.