[header] How to sleep in your car on a road trip [title] Bring comfortable bedding. [step] Whether you're parking for the night or taking a couple hours' snooze break while your friend drives, you'll need to make up for the car's environment. While not impossible to sleep in cars as-is, it can be uncomfortable. 
You'll probably bring a bit more if you plan to sleep overnight and not just during the drive. [substeps] Must-haves are pillows and blankets, or a sleeping bag if you are traveling through regions with cold temperatures.