China vehicle sales in January fell by the largest margin since 2015 for several global automakers, with General Motors Co and Ford Motor Co blaming the roll back of a tax cut on small-engined vehicles and the Lunar New Year holiday. Ford Motor said on Thursday that its sales fell 32 percent year-on-year, while GM said sales dropped 24 percent, making the biggest drop since the two automakers first began reporting data for retail sales of their vehicles in China in the second quarter of 2015. China's central government raised the purchase tax on cars with engines of 1.6 liters or less to 7.5 percent this year from a special rate of 5 percent last year, a policy originally instituted to shore up sales in a weakening economy.