Philadelphia 10 hours ago Philly school district unveils cleaner buses The School District of Philadelphia is set to unveil new buses that use clean energy. The propane autogas buses are said to run about 96-percent cleaner than diesel. US & World Videos 8:01 ‘Roll'ing toward the end: The Lineup 2:51 ‘Are you hungry?': What it takes to make perfect empanadas 1:47 Philly schools keeping student athletes safe with new football helmet covers 2:01 ‘I'm bummed.' Fans excitement turned to disappointed after Sixers lose home opener 1:55 Philadelphia School District's television studio gets huge makeover