Deceleration Overshoot (alpha)¶

Deceleration overshoot is an optional toggle for Smart Cruise. It compensates for the Mazda ECU's slow response to a lower set speed.

The problem it solves¶

MRCC, the stock Mazda radar cruise, reacts slowly when you ask it for a lower speed. Before a curve, the car starts braking later than the planner expects. The car enters the curve too fast.

What the toggle does¶

When a slowdown is coming, zoompilot asks for more deceleration than the model wants, earlier. The overshoot makes up for the ECU's lag, and the car gets the deceleration the curve actually needs.

Status¶

This feature is marked alpha. It shipped in the 2026-07-04 release. If braking into curves feels too strong with it on, turn the toggle off and report the route in the zoompilot Discord.

Design details¶

The publication path from planner to long controller is described in Curve and limit speed planning.