Presumably, you are not interested in the distance traveled during just any 3-second period. You probably want to know the distance traveled during the 3-second period of acceleration from 0 to 60 mph.
The average speed over that distance is 30 mph = (1/2)(0 mph + 60 mph). The distance traveled in 3 seconds at 30 mph is
(3 sec)*(30 mile/hour)(1 hour/(3600 sec)) = 90/3600 mile = 1/40 mile
= (1/40 mile)(5280 ft/mile) = 5280/40 ft = 132 ft.
A car that can accelerate from 0 to 60 mph in 3 seconds can do so in 132 ft (if the acceleration is constant--which it rarely is with a car).
The average speed over that distance is 30 mph = (1/2)(0 mph + 60 mph). The distance traveled in 3 seconds at 30 mph is
(3 sec)*(30 mile/hour)(1 hour/(3600 sec)) = 90/3600 mile = 1/40 mile
= (1/40 mile)(5280 ft/mile) = 5280/40 ft = 132 ft.
A car that can accelerate from 0 to 60 mph in 3 seconds can do so in 132 ft (if the acceleration is constant--which it rarely is with a car).