As Michelle Wirth tells it, she and her husband fell in love with Mercedes-Benz -- and then fell in love with each other. She started working for Mercedes Benz 15 years ago as a mechanical engineer. Her husband, Peter Wirth, is from a town near Stuttgart, Germany, where Mercedes-Benz has its headquarters. He was working there when they met. Now the couple, along with business partner Rich Hesse, are just weeks away from opening a dealership -- Mercedes Benz of Springfield -- at 295 Burnett Road in Chicopee.