When it was launched less than a year ago, the $2,500 Tata Nano was promoted as a safe, ultra-cheap car for poor Indians, an alternative to the motorbikes that zoom precariously around the country. New questions about the safety of the pint-sized auto are being raised, however, after one of them burst into flames Sunday as it was being driven home from the showroom. Software engineer Satish Sawant, his wife and 5-year-old son escaped from the silver Tata Nano — which still bore a celebratory garland of marigolds on the front hood — before the tiny car was engulfed by...