For this kind of video, people often don’t record 40–50 hours of normal video continuously. Instead, they shoot a time-lapse: one still frame every few seconds, then assemble those images into a video later. That greatly reduces storage needs and gives better control over quality.

Based on the answers, common options are:

• a smartphone or tablet with a time-lapse app
• a Canon compact or DSLR that supports CHDK or Magic Lantern interval shooting
• a webcam connected to a small laptop/netbook

A Canon camera with an intervalometer setup is a practical choice if supported by CHDK or Magic Lantern, but use unofficial firmware carefully since it may carry some risk.

For very long shoots, external power is important. You’ll likely need to keep the camera powered from the car or another continuous power source, because batteries usually won’t last through an overnight sequence.

For storage, save still images rather than full-length video, then stitch them into a movie on your computer with time-lapse software. That’s the usual way to achieve long, high-quality driving time-lapses without needing an impossibly large memory card for uninterrupted real-time video.