My first attempts just had the Milky Way together with the silhouette of mountains. But when I opened the car door, the interior light of the car automatically turns on for about 30 seconds and I noticed an interesting light pattern on the ground.
It took some experimenting to get the right balance between the brightness of the car and the brightness of the stars. For this image, I used the following procedure. I released the shutter, then walked to the car, opened and closed the door to trigger the automatic lighting and quickly walked away. In that way, the car light contributed for about 10 seconds to the total exposure time of 20 seconds, and motion blur prevented that I became visible in the image.
3200 ISO, focal length 14mm, 20s at f 3.2.