Let's try it this way Giblet, if your vehicle is 1000 kg and travels at 30 m/s (108 km/h),
it will carry a kinetic energy of 1000 * 30^2/2 = 450 kJ or kWs
If you bring that car to a standstill in 90 meters at a constant de-accelleration, it will take you 90/(30/2) = 6 seconds
and your "braking-power" is 450/6 = 75 kW (100 Hp) during that time.
But remember, if you want to recover that energy, locking the wheels is a no-no.
"Bernoulli is a nine-letter name"