VAO (Vía de Alta Ocupación) is the Spanish name for HOV lanes. Madrid has been working with a VAO lane on one of the main entries of the city, via the A6
highway (Northwest). This lane is usually used only by public transport, but the Regional Government of Madrid has decided to allow private motorists to enter the lane as long as cars are used by more than one person. In order to promote carpooling, the regional goverment has created a website
where motorists can share their rides and find partners. It's free and it allows people to plan their trips as well as choose route mates based on gender, age, smoking preferences and schedules.
[Source: Comunidad de Madrid