 All oval tracks in any of NASCAR's National Series (except Eldora) use the SAFER Barrier and other soft wall technology to lessen impacts.After a series of flips and dangerous crashes in the 1980s, NASCAR began requiring all cars to run a restrictor plate at Daytona and Talladega.The restrictor plate limits air into the engine, reducing horsepower and speed at these tracks from 230-240 mph to 195-200 mph.