Controlling to pixelblaze

That’s correct! The Getting Started page goes through all the steps. You’d follow the “create AP” flow.

In your car, connect a phone to the WiFi the Pixelblaze creates and go to http://192.168.4.1 and you’ll see the control interface.

You may wish to test the 2.4Ghz reception in your car setup since there’s a lot of metal in a car. I’ve never tried, but hiding the PB board in the bumper might not provide a strong enough signal.