Indian automakers will this week urge the government to lower a proposed sales tax on hybrid vehicles, as they fear the planned rate could make development of the technology unviable, industry sources and executives said. India said it would tax hybrid vehicles at a rate as high as 43 percent under a new unified tax regime set to come into effect from July 1. That would be significantly higher than the prevailing tax of about 29 percent on such cars. India's auto trade body, whose members include companies such as Maruti Suzuki, Mahindra & Mahindra and Toyota Motor Corp, will push to lower the proposed rate, an industry source involved in the matter said. If the tax is not reconsidered it will essentially make all hybrid cars unviable, R.C. Bhargava, Chairman of Maruti Suzuki, the country's top-selling carmaker, said.