Blockades by Italian lorry drivers on strike over fuel prices have led to the country's biggest car-maker, Fiat, halting production at five factories.
Roads in many areas of Italy have been blocked and Fiat says the move has affected supplies of components.
The strikers are unhappy with increased fuel prices introduced in a series of austerity measures last month.
Police say a protester died in an apparent accident involving a German lorry driver in the town of Asti.
The driver, a 52-year-old woman, was being questioned by police in the northern town, Italian media said.
The strike, which followed protests that brought much of Sicily to a standstill last week, began on Sunday night and caused disruption on routes near some of Italy's biggest cities for the second day on Tuesday.
Motorways were affected near Naples in the south and Turin, Bologna, Genoa and Milan in the north as drivers blocked toll-booths and most of the lanes, creating havoc for commuters.
The lorry drivers are particularly incensed by a fuel tax increase, put forward by Prime Minister Mario Monti's government, that has raised petrol prices by 8 cents a litre to around 1.76 euros (£1.47; $2.29).
Further government plans to open up a number of professions, including cab drivers and pharmacists, to greater competition have also aroused anger, prompting strike action by taxi drivers on Monday.
Industrial action is also threatened by petrol station owners, pharmacists, railway workers and lawyers.
Petrol supplies are said to be running low in Naples and there are concerns for food distribution in the southern region of Calabria, reports say.
Production at Fiat's plants at Pomigliano, Cassino, Melfi, Mirafiori and Sevel Val di Sangro had to be stopped on Tuesday morning and the company said work would not resume later in the day.
The lorry drivers want the government to make it easier to claim back fuel tax as well as tougher action on unlicensed operators.