CAR thieves are again preying on drivers who leave their car engines running to defrost windows.

Four cars have been stolen from outside homes in Bolton over the last week alone.

Three other cars, one a £30,000 BMW, were stolen in the last icy snap in January.

In the latest theft yesterday morning, an Audi was taken from outside a house in Westhoughton. Police said the owner went back inside his home, leaving his engine running.

A BMW and a VW Sirocco were stolen from homes in Egerton and Horwich over the last few days.

Police do not believe that the thefts are the work of a gang. They say the cars stolen in Bolton have been taken by opportunist thieves targeting expensive cars.

Today detectives told drivers to take care -- and warned them that leaving cars running in public is a criminal offence.

Det Chief Insp Steve Heywood, of Greater Manchester Police's autocrime unit, said: "Drivers should remain with their vehicles at all times."

During the cold snap early last month, ice bandits stole cars across Greater Manchester.

Thieves stole a 37-year-old motorist's BMW from outside his home in Saxby Avenue, Bromley Cross.

A 52-year-old's £25,000 BMW was taken from outside his home in Marlborough Close, Ramsbottom and a Ford Mondeo was taken from an address in Bury.

Other expensive cars have been stolen in Moston, Ashton-under-Lyne, Standish, Salford and Oldham.

Insurance companies also have differing views saying they would look at individual cases on merit.

But many said that there would be no cover for the loss of a car by theft if the keys are in the vehicle.