The quickest cars are no match for even the most mediocre motorcycles, and in many cases the chase is effectively over in seconds when the motorcycle simply disappears from sight. A Ford Crown Victoria like those used by many police departments in the United States takes over 10 seconds to accelerate to 60 miles per hour. An average sportbike will do it under 4 seconds. Modern sportbikes can do this in well under 12 seconds. Most sportbikes will also easily surpass 120 miles per hour, which is the limit for most police cruisers.
Bikes have superior maneuverability compared to cars.
A sportbike can turn better and simply fit more places than a car. You just don't need the room a car needs. This makes it possible to slip out of the car's grasp quite easily. Motorcycles generally have better brakes than police vehicles. These come in handy because for every acceleration, there is an equal and sometimes more urgent deceleration.