Ryan Blaney has the fastest practice speed during practice 1 of 178.992 mph for the 2018 NASCAR Cup Series Overton's 400 at Chicagoland Speedway.
The practice speeds table shows the fastest lap during practices.
|Driver||From Lap||To Lap||Average Speed|
|Martin Truex Jr||3||12||172.771|
|Darrell Wallace Jr||18||27||168.570|
Cars must run 10 consecutive laps on the track to be included in this table.