It's taking a lot of the carbon from the soil instead of the air... so no. Also, consider all the gasoline used to plant/harvest/transport it. Ethanol is a corn-state boondoggle. It drives up corn prices and brings in massive revenue to the midwest. Ethanol support is critical for any politician that wants to win in states like Iowa. When you hear a 60yr old farmer start talking about "green energy" you know he grows corn.
But the vast majority of the carbon in corn comes from the air, not the soil! It might surprise you to learn that most of the bulk of a huge tree, for example, was produced from the air, not the ground. The ground supplies trace minerals and water, and little else.
Another real problem with ethanol is that it is a low energy density fuel, compared to gasoline. So beyond a certain small percentage, it actually reduces the efficiency of your vehicle and causes it to burn MORE gasoline per mile, rather than less, which negates the advantages of using ethanol in the first place.