From about 1920 to 1930, car manufacturers began creating a closed body on the vehicle. This protected the driver and passengers from the weather. Vehicles began using curved glass and the new enclosed bodies gave a sense of privacy. Heaters were added for comfort. Many of the features of modern cars came from this period. These include four-wheel drive, front-wheel drive, and hybrid electric vehicles. Safety glass protected those inside the car from sharp glass in cases of an accident. By the end of the 1920s cars were becoming faster and were showing a level of style and beauty.