The sport coupe is having a moment. And here's why: Carmakers have finally found ways to create performance models that are strong, sturdy, and lightweight. This is a big trend in the world of sexy two-door cars, boosting both acceleration and gas mileage. The primary credit goes to nimble materials like aluminum and carbon fiber, which help trim the fat off car designs and reduce carbon gas emissions. Beyond those things, however, these new-to-the-market cars all go in separate directions.