A downturn in vehicle sales in Europe and a decided easing of growth in the Asia/Pacific region slowed the auto industry’s global recovery in May.

Auto makers registered a 14.6% sales increase in the month, marking the lowest year-on-year gain so far in 2010.

May’s 6.28 million worldwide vehicle sales represented a 1.6% uptick from the prior month and brought deliveries through the first five months to 31.1 million units, 22.6% ahead of like-2009.

Related document: World Vehicle Sales Summary

With government incentives expiring and consumer prices rising in China, May sales outpaced year-ago by just 28.4%, compared with the country’s 55.4% growth year-to-date.

May sales in Japan (+22%) and India (+39.3%) were more in line with year-to-date growth in those markets, but overall Asia/Pacific results rose a mere 26.7%, compared with 43.3% in the first five months.

The phasing out of scrappage schemes across Europe continues to hurt performance in the region. Deliveries fell below year-ago for the second consecutive month, down 3.7% to 1.62 million cars and trucks.

Declines in Germany (-32.7%), France (-8.8%) and Italy (-12.4%), the region’s three largest markets, were offset somewhat by sizable gains in the next three markets – the U.K. (+14.6%), Russia (+32.3%) and Spain (+37.7%), where government incentive programs helped boost deliveries.

Year-on-year improvements in the U.S. (+19.1%) and Mexico (+16.9%) combined with near-flat sales in Canada to drive North America vehicle sales up 16.4% in May.

U.S. deliveries were sparked by larger-than-normal sales to rental companies, as retail demand in the market remained relatively stagnant.

Argentina’s 31% jump in vehicle sales in the month, paired with a 10% rise in Brazil, lifted South America results 12.8% above like-2009.

Asia/Pacific accounted for 40.3% of world sales in May. Europe represented 25.8% and North America 21.3%, its largest share since last August. South America made up 7.8% of all vehicle sales last month, its highest share for the year.