Quote Originally Posted by WRCStan View Post
Looking at kinetic energy values, 10x appears only really useful at high speeds at realistic efficiencies, stages where you won't be needing the boost so much anyway.
I think you undersestimate the deceleration value a lot. Let's say you need to slow down the Rally1 car from 150 km/h to 100 km/h on asphalt (from 42 m/s to 28 m/s). The car has around 1400 kg with the crew. The kinetic energy at the start of braking is 1,235 GJ. The kinetic energy at the end is 0,549 GJ. You need to take away 0,686 GJ of energy. Now the crucial part is how fast you do that. Let's say it happens at an average value of 2G which is for sure possible, I guess it's more in good conditions but on the other hand a reasonable part of the braking energy is taken away by aerodynamic drag and I completely omit that here. If we stick with these values it means that it takes 0,7 seconds to slow down from 150 km/h to 100 km/h. 0,686GJ at 0,7 seconds means 970 kW braking power.

For sure it's just a very simplified example but I guess it can make an idea about the magnitude of the values.