On August 18, 2016, Byron and Hendrick Motorsports announced they have signed a multi-year driver agreement, with Byron running full - time in the Xfinity Series driving the No. 9 Chevrolet Camaro for JR Motorsports in 2017. Byron finished 2nd at Michigan, just losing out to Denny Hamlin. One week later, Byron won his first career race at Iowa after Christopher Bell wrecked late in the race, battling for a win with Ryan Sieg, who eventually placed second. He ended up winning again the week later in an overtime finish at Daytona. Byron also won at Indianapolis Motor Speedway for the third Xfinity victory of his career; he would add a fourth win when the series visited Phoenix for the penultimate race of the season. The Phoenix win also placed Byron among the four drivers eligible to race for the series championship at Homestead - Miami Speedway. At the final race in Miami, Byron held on as he finished 3rd, ahead of his Championship 4 teammate, Elliott Sadler. He won the 2017 NASCAR Xfinity Series Championship
who did william byron drive for last year
JR Motorsports