In nearly 700 European towns and cities, automobiles are persona non grata today. It's car-free day, an idea intended to promote alternative forms of transport that pollute less.

Fourteen countries are trying out the car-free idea.

But there's still a long way to go before Europeans switch to subways, bikes, trams, or walking.

Bikes take to the streets in Europe

The car-free day started in France in 1997. In Paris, a few streets are usually blocked off, and traffic jams form around the car-free area.

Frequently, businesses complain that sales drop because no one drives by to shop – but there's a cost to having cities filled with cars, too.

Medical researchers say six per cent of deaths in France are caused by diseases related to air pollution. Treating those people costs about 1.5 per cent of the country's gross domestic product.

Rome

But perhaps the most persuasive argument for car-free cities in Europe these days comes from OPEC – skyrocketing pump prices are causing many to re-think how they get around.