Car Pooling is only a great idea when 3 or more people are involved.... this spreads out the cost of fuel easier and you guys can each change cars each day to reduce overall wear and tear so that you'd only use your car 2 or 3 times a week, depending on the rotation.
Just 2 people.... no very viable.
Wait - why isn't a 2 person car pool viable? You're still cutting your fuel consumption in half. People do this all the time. Where's the downside?