From the Store description:
Follow the excitement of the 2016 season with the Official App of NASCAR. NASCAR for Windows 10 provides a comprehensive user experience in a customizable format. Follow your favorite driver with targeted news, video and social content. Get access to the live leaderboard, in-car cameras and driver audio during live races. And with Windows 10’s unique split-screen function, you're always one touch away from purchasing tickets or checking your fantasy lineup.
- Live Race Leaderboards for all NASCAR Series
- Lap by Lap commentary
- Real time News, Video and Social Media
- Complete Schedule, Standings and Manufacturer Standings
Premium Live Features (Subscription Required):
- Live Premium Leaderboard - Premium Leaderboard with exclusive data points
- Live Driver Audio - Listen to the In-Race strategy between Drivers, Crew Chiefs and Spotters - Exclusive to Sprint Cup Series and XFINITY Series races
- Live In-Car Cameras - Follow the action from the driver seat with Live In-Car cameras - Exclusive to NASCAR Sprint Cup Series races only
- Live Broadcast Radio & Officials Radio - Listen to the official NASCAR radio for every race of the season - NASCAR Officials Radio is available for all Sprint Cup Series races
So a good mix of free and premium features then. We won't worry too much about the latter being in dollars since presumably you'd have some USA interest or location if you were interested in NASCAR in the first place.
Some screens of NASCAR in action on Windows 10 Mobile: