Justin Marks claimed the fastest speed in the first of two Xfinity Series practice sessions Saturday at Road America in Elkhart Lake, Wisconsin.
Marks covered the 4.048, 14-turn road course with a top speed of 107.923 mph.
Christopher Bell, driving the No. 18 Toyota for Kyle Busch Motorsports, suffered transmission failure, prompting his team to replace it. He managed just one lap of practice before he took the car to the garage.
Bell is expected to be ready for today’s second practice at 4 to 4:55 p.m. ET.