Instead, Mr Sanchez, 35, upset by his wife's threat of divorce, turned his newly- purchased Glock 9mm automatic pistol first on Stephanie, 8, as she sat in the front of his Toyota, then on Sasha, 5, in the back.
Police believe Mr Sanchez, a Guatemalan immigrant described by neighbours as a workaholic, drove around for hours before pulling into his driveway on West 37th Street in Miami's Hialeah district.
His wife and lifelong sweetheart Maria, 27, who had waited for them into the small hours of Saturday, was startled by a gunshot. She ran outside and found her husband slumped over the wheel and her daughters' bodies.
Police said Mr Sanchez, who worked seven days a week at his flower import business, left a suicide note saying he was not to blame for their marital problems. "So I'm taking with me what's mine. You can keep what's yours," it said.
The price tag was still on the pistol, which he had picked up on Thursday for $499.