The vintage period in the automotive world was a time of transition. The vehicle started off in 1919 as still something of a rarity, and ended up, in 1930, well on the way towards ubiquity. In fact, automobile production at the end of this period was not matched again until the 1950s. The classic vehicle era was well in the pre 1920s. In the intervening years, most industrialised states built nationwide road systems with the result that, towards the end of the period, the ability to negotiate unpaved roads was no longer a prime consideration of automotive design. Cars became much more practical, convenient and comfortable during this period. Car heating was introduced, as was the in-car radio. Antifreeze was introduced, allowing water-cooled cars to be used year-round. Four-wheel braking from a common foot pedal was introduced, as was the use of hydraulically actuated brakes. Power steering was also an innovation of this era. Towards the end of the vintage era, the system of octane rating of fuel was introduced, allowing comparison between fuels.