In recent years LEDs are appearing on the market that contain a controller chip. Currently the WS2812B is highly popular. It is a RGB LED that contains a simple chip inside. The LED is controlled through a single pin using a serial shift-register-like protocol. Multiple LEDs can be chained together; like a Christmas light.
The WS2812B LED on a breakout-board for convenient mounting.
The WS2812B is an RGB LED with a built-in shift register like controller. It has 4 pins: GND, Vdd, Data-in and Data-out. With only three wires going from LED to LED, one can control each LEDs color and brigtness individually.
Using such LEDs makes wiring up a vehicle very easy: one only needs to run 3 wires from one LED to the next.