The swift move follows the official announcement on 27 September by King Salman that the country's ban on women drivers will end in June next year.

The decision has immediately created a potential new market of several million, very wealthy, potential car buyers.

Among the firms using Twitter for their adverts are VW, Ford and Nissan.

According to the Bloomberg news agency, the biggest sellers of cars in the country are Toyota and Hyundai, whose SUVs (sports utility vehicles) are especially popular.

Saudi Arabia has a population of 29 million, of whom about 20 millions are citizens.

The country's wealth from decades as the world's biggest oil producer means that some Saudi nationals are among the world's richest people.

The country's ban on women obtaining a Saudi Arabian driving licence, or driving in the country, was unique.

The big change to that long-standing policy could pose a threat to the jobs of an estimated 800,000 or so foreign chauffeurs who are employed in the country to drive Saudi women.