Mach number a small area around the object's leading edge. (Fig.1b) Fig. 1. "Mach number in transonic airflow around an airfoil; M < 1 (a) and M > 1 (b)." When an aircraft exceeds Mach 1 (i.e. the sound barrier), a large pressure difference is created just in front of the aircraft. This abrupt pressure difference, called a shock wave, spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone). It is this shock wave that causes the sonic boom heard as a fast moving aircraft travels overhead. A person inside the aircraft will not hear this.
Mach Five protagonists build the Mach 6. The Mach 6's engine is not designed to run on gas, which is a crucial story point, even though gas is still used for it through most of the series. It has all the features of the Mach Five, but redesigned or changed in some form or another. For example, the rotary saws are kept, but they're turned into laser saws, and the blades can pivot so things that are over head can be cut. The new car features a transparent, holographic screen over the dashboard that the driver can use to interact live with