1/87 Smart DIY micro RC car

I have converted the 1/87 scale BUSCH Smart Fortwo into the radio controlled model.
The steering is operated by 3.9mm diameter stepper motor and the drive by 4.1mm diameter DC motor.
Wireless communication is performed by two Bluetooth modules(RN4871U).
The RN4871U must be configured for communication before assembly.
The transmitter is built on the breadboard.
The microcontroller used is ATtiny3217 on the transmitter and ATtiny1616 on the receiver(the car side).
When the car decelerates from a running state, the brake lights light up automatically.
Headlights and turn signals are operated manually.
When the voltage of the Li-Po battery becomes 3.4V or less, the turn signals stay on instead of blinking.
The power supply for charging is DC 5V.
Even if Bluetooth communication is interrupted, it will be automatically reconnected.
The grid of the cutting mat in the video is 5cm square