But that doesn't factor in the fact that with owning a car you have to pay maintenance costs and insurance.
My monthly insurance average with comprehensive coverage is about $65 (although I only pay a lump sum every 6 months). My weekly gas would be about $35-$40 (depending on the price of fuel and the fuel I choose to use - if it's summer, I'll chose E85, which with the subsidies that bring its price down, I've paid as little as $25 to put 8 gallons of E85 in the summer, though E85 is not a good cold weather fuel as it's managed to gum up the fuel filters on the cars we have that can use it, so we put in unleaded from late October to mid-April), but I average only about 200 miles a week. My brother averages about 400 miles a week, filling up his 20 gallon minivan tank twice a week at between $120 and $140 a week.
Then there's oil changes every 3 months/3000-4000 miles that cost $30 without coupons and between $10 and $20 with coupons. And with my older car I have an average of $200 to $400 worth of work every 3 months or so. If I were a gearhead it'd probably average out to that still, but I'd probably have been able to notice more wrong with it and diagnose more myself and have fixed it. And then every 3 to 5 years (depending on the length of the battery's warranty) you have to replace your battery or you'll have issues where your car may not start because the battery is dead and won't hold a charge. And tires need to be changed every few years, which gets expensive. For instance, on my car, it'd probably be $300 to $400 for new tires, while on my brother's minivan (which needs them now) it'd run us $400 at our preferred shop (which is preferred for us because they don't charge exorbitant fees for labor and parts), and larger tires for larger vehicles could easily climb up near and over $1000.
When you buy a car, you also are taking a gamble on whether it'll have any issues. Often, many people will sell their car rather than fix the problem if there's something they've encountered, so you'd want to ask if you can have a shop look at the car to see if there are any major issues. If they don't let you, they're probably trying to hide some major problem the car has. If the deal sounds too good to be true, it probably is. My car has kind of been a lemon since I bought it. I've sunk around $4500 worth of work into my car (one I bought for about $2800) since I bought it a year and a half ago. Although a large chunk of that went into the cooling system within the first 3 months ($500 for a water pump, $1500 for a leaking and damaged head gasket, plus another $300 or so for other work I figured was worth having since I was probably going to be without it for over a week anyway. And then there were the labor charges).
tl;dr: A car is expensive to own