In the future, cars will become much better than they are today. They are being developed in order to make the cars safer, cleaner, and sustainable. Today, there are more and more hybrid cars, electric cars, and fuel cell vehicles. The energy they will use include hydrogen, electricity, and even compressed air. Many other technologies are used to improve energy efficiency. For example, the regenerative braking saves and stores energy as backup power. This is used in hybrid vehicles. Another example is Vortex prevention devices in order to reduce air resistence.