But ride-hailing services and autonomous cars are going to revolutionize parking in cities across the country — in garages, in lots and along curbs. By 2030, 15 percent of new cars sold will be totally autonomous, according to one estimate. One in 10 will be shared. And as it becomes easier for people to summon shared or autonomous cars when they need them, fewer people will want to own their own vehicle, meaning fewer cars overall.