My son tells me he wants to do underglow on his 2011... Let me preface this by saying I am a programmer and I like to call myself a maker as part of my hobby so it's in my nature to DIY the whole thing.
I wanted to be able to have multiple colors under the car so I started there. That led me to 5050 LEDs but they were not individually controllable. I then found some interesting projects online using WS2812 LEDs and this started the wave that followed.
I took 10M of LEDs and connected them to an Arduino Mega. Never having programmed a microcontroller it took me a little time to figure it out, but within a weekend I was controlling the LED strip.
Next I wrote a few dozen animations but it quickly became annoying to step through the animations with the single button I wired up. I moved on adding a Bluetooth shield to the Mega. With the BT controller in place I could now write an Android app to control everything... also my first time to code Android.
The Android app tells the controller what animation to play. While the Arduino is playing the animation you can control speed and color via the app.
... some of the animations are a little muddy as this was the first time to run it on the car. Now that it's on the car I can see how the light hits the ground and fix the animations. In this version you can see some animations are not bright enough and some are just not defined well. This is due to the pixels diffusing more than I anticipated. I will make adjustments for version 2.
Anyway if you've made it this far I'm sure you want to see the video.
Sam