By Justin Webb BBC Europe correspondent

The German car maker, BMW, says cars in its new 7-series will have the same basic price, excluding taxes, in all 12 eurozone countries.

Exchange rates will no longer be a problem for car buyers in the eurozone

The high margin 7-series is BMW's latest model and went on sale in Germany during the autumn.

Eventually, prices will be harmonised for all BMW's models.

It is an announcement of huge potential significance, with the cost of a car ranging at the moment by as much as 20%, depending on where in Europe it is bought.

People queued to get their hands of euro notes and coins when they were introduced

But it is also a sign of the pressures on all firms selling all products in the European market to justify differences in pricing or abandon them.

In the longer term, the European Commission believes that prices in the wealthier European nations will fall towards levels currently charged in southern Europe, because to do the opposite and increase the lower prices would lead to a huge drop in sales.

The commission welcomed the BMW announcement.

All shops must eventually justify or scrap price differences

On the fourth day of trading with the new euro notes and coins, most people and most businesses appear to be coping well, though there are concerns about Italy, where the majority of cash transactions are still taking place in lira.

The Italian prime minister, Silvio Berlusconi, has been forced to reiterate the Italian government's commitment to the Euro, after some of his Euro-sceptic cabinet ministers poured scorn on the project.