Hemp is a plant, and like all plants, hemp removes carbon dioxide from the atmosphere....only much, much faster. Trees for instance, take 20 years to grow, while hemp by contrast, matures in 3 to 4 months, and depending upon climate, can be replanted several times a year.
If you've ever wondered why hemp was used for rope, sails, clothing and paper for thousands of years, it's because hemp's fibers are incredibly strong... dense with the carbon that hemp sucks out of the air. So when hemp is used to manufacture a durable good like a car, all that CO2 that hemp removes from the atmosphere, is removed. This process is called carbon sequestering. And making everything we can from hemp is an effective means of reversing climate change.
Is it because hemp is lighter than steel or fiberglass, making a car more efficient? Is it because hemp resists dents and isn't brittle like carbon fiber? Is it because hemp is biodegradable? Yes, yes, and yes again. These are all great reasons for using hemp when manufacturing a car.
To learn more about hemp, watch Hempsters, Plant the Seed.