First, let's look at your cost for public transportation. You are going to pay for a pass to use the bus, train, light rail, etc. These passes can be purchased for one time use, or you can buy a monthly unlimited use pass, etc. In some cases you get passes for free, such as for being a student. How much the pass costs will depend on where you live, and how much you intend to use public transportation. However, even in the more expensive areas, you can still save. The reason is, you pay for the ride, you do not have to pay extra if one of the busses breaks down, or if the light rail needs to be cleaned. You do not pay more when they get an insurance hike because of an accident, etc. If you were to drive yourself, you would.

Second, let's look at the various ways a public transportation pass saves you money.

• #1: You will not have to buy a car, or a second car. If you and your spouse have one car, and you both work, you are faced with the choice of trying to coordinate schedules to drop or pick one another up, buy a second car, or use public transportation. If you choose to use public transportation rather than buy a car, not only will you save the cost of the car (usually between $200-$300 a month) but you will also save on car insurance (about $65 a month). The savings on the insurance alone will cover the cost of your bus pass. So, using public transportation in these circumstances, or ones similar will save you over $3000 a year.
• #2: The cost of fuel. According to studies, most people spend upwards of $2000 a year on fuel for their car. When you buy a public transportation pass you are basically splitting fuel cost with several hundred people. When you drive yourself, you are not splitting it at all. This means if you can replace half of your driving with riding public transportation, on average you will save $1000 a year. If you minus out the cost of the pass for the year, you are still going to see several hundreds of dollars of savings each year.
• #3: Wear and tear on your car. The cost of driving is not just gas. You wear your tires out, and they need replacing. You clog filters, wear out belts, make your engine slower, etc. The cost to maintain a car can be high, so if you cut your driving in half, you can cut that cost in half as well. You will need to replace your tires less frequently, get oil changes less frequently, and not need tune ups as often. This results in several hundred dollars of savings each year.