Tata Motors (TAMO.NS) is upgrading the starter motor of all old Nano models to the one installed in its new 2012 edition, launched in November, a spokesman said on Monday. The replacement being offered to all customers, free of cost, was not due to any safety concerns, he added.

A starter motor is an electric motor which helps in rotating an internal combustion engine to initiate the engine's operation under its own power.

The Financial Chronicle, on Monday, reported that the cost borne by the company on about 145,000 Nanos sold till date could be around Rs. 1.1 billion. The spokesman did not divulge the cost that the company will bear on this account, saying it was immaterial.

The four-seater car, which is the world's cheapest, costs as little as Rs. 1,40,000 and was launched in a blaze of publicity in price-sensitive India.

In November, Tata offered Nano owners the option to install safety protection in their vehicles after local media reported that seven cars had caught fire. The carmaker then said it was not a recall as the fires were specific to the units.