New Delhi, June 21 -- Retail sales of vehicles across categories declined by 7.5% to 1.77 million units in May, impacted by a slowing domestic economy and continuing liquidity crisis in nonbanking financial companies, shows data published by Federation of Automobile Dealers Associations. The decline in retail sales of passenger cars was halted after significant production cuts by manufacturers, but two-wheeler and commercial vehicle sales fell significantly. Retail sales of passenger vehicles decreased by just 1% year-on-year to 251,049 units, with manufacturers reducing wholesale dispatches. Maruti Suzuki India Ltd, the country's largest auto manufacturer, reduced wholesale dispatches by 23% to 125,552 units, Hyundai Motor India Ltd by 5.6...