Local directions site HopStop keeps coming up with new ways to differentiate itself from GoogleMaps. First they started telling you how many calories you burn on your commute and now they've added a nifty carbon emissions calculator to their search results.

The carbon emissions calculator is meant to allow users to "quantify the positive impact of their transit-based travel on the environment, as compared to driving a car," and is available for all non-car directions. So, for instance, we now know that when we take the train to work instead of driving—Ha! Still need to get that license—we're helping save .48 pounds of carbon emissions from entering the environment. If we take the bus, we save about .51 pounds. And if we bike? Oh, if we bike we save about 2.5 pounds of carbon emissions from polluting our planet. Roughly.

Between the calorie calculator, the emissions calculator and their now-integrated taxi fare calculator, HopStop is clearly working hard to stay in fighting shape against the giant from Palo Alto. So, how many pounds of carbon emissions do you save with your commute?