While the three options are fairly similar, carpooling in a regular car with one other person uses less fuel per passenger than either driving alone in a hybrid or carpooling with two additional people in an SUV.

To put it simply, when you add more people to your commuter vehicle, your fuel economy is effectively multiplied by the total number of people in your car. If you drive a car that gets 24 miles per gallon, it will take one gallon of gas to transport you alone 24 miles. When you add another passenger, that same gallon of gas will transport you and your passenger 24 miles. You’re now getting 48 passenger-miles per gallon.

Here’s a table that breaks down the fuel required per person to drive 400 miles. You can use this table to compare the fuel efficiency of different types of vehicles and different numbers of passengers.

Driving the hybrid is clearly the most fuel-efficient choice. However, not everyone can afford a hybrid. If that's the situation you're in, what can you do to achieve hybrid-level fuel economy? One way is to start carpooling. If you drive a small or midsize car and carpool with just one person, you’ll save gas equal to what you'd save with a hybrid. If you drive a less fuel-efficient car, truck, or SUV, consider forming or joining a three-person carpool.

In addition to saving you fuel, money, and wear and tear on your vehicle, carpooling results in fewer cars on the road, less traffic, shorter commuting times, and (believe it or not) happier people.