One key is to make sure the tail-lights paint a nice graphic line through the frame such as an s-curve. This can be a little tough on a flat prairie!
Although there was a fair amount of light pollution, some of the stars popped through nicely. With a wide lens like my 16mm lens, you can usually leave the shutter open for about 30 seconds before the stars start to blur. The general rule is to divide your focal length (in full frame camera terms) into 500. Here, 500/16 = 31 seconds of expsoure to keep sharp stars.
Night-time streak of car taillights on Blackland Prairie at Clymer Meadow Preserve, Texas Nature Conservancy, Greenville, Texas, USA.
Canon 1Ds Mark III. 16mm lens. ISO 800. f/5.6 @ 30 seconds