Tomorrow is Earth Day, and everyone is talking about the real steps people can take to fight climate change. What are you going to do this year? Buy a hybrid? It's a popular choice: The hottest hybrid models continue to cruise off car lots faster than dealers can restock. But is that hybrid really better for the environment than the standard car several aisles over? Or even, for that matter, your old car? This is simple math, folks: The higher the miles per gallon (mpg), the greener the car. So if you have your eye on a hybrid SUV that gets less than 33 mpg in the city and 30 mpg highway, ask yourself this question: Are you looking to do something for the environment? Or are you searching for a socially acceptable excuse to upgrade? If it's the former, step away from the SUV, and visit this EPA website for some other options.