Fiat's sales in Europe have plummeted over the weak economy and a saturated market demand for vehicles from Italy's biggest carmaker.
Sales fell 12.1 percent compared to May 2011, giving it a 7.2 percent market share in Europe, compared to 7.5 percent year-on-year.
In the 27-member European Union, the Turin-based company has sold 82,500 cars in one year.
The economic slowdown has prompted consumers to spend less as workers lose jobs and companies cut spending.
Fiat at the end of 2011 shut down an Italian plant, the first European automaker to close a production plant in its home country since economies were sent into a tailspin by the 2008 financial crisis.
The company has sold 16.6 percent fewer cars during the first five months of the year.
The sales include cars from Chrysler, the American auto company controlled by Fiat.
Fiat and Chrysler chief executive officer Sergio Marchionne says he aims to combine Italy's top car company with the America's No.3 by the end of 2014.