Global auto makers sold 6.92 million vehicles in September, the highest monthly result since March and the second-highest increase in 18 months.

September’s tally represented a 6.6% gain over year-ago, albeit a slight dip from the 7.2% increase in August.

But it was a significant improvement over the 2.3% growth the industry averaged from March to July in the wake of Japan’s tsunami and earthquake.

September’s gain was fueled by a 9.5% jump in North America, where the U.S. (+10.7%), Canada (+0.2%) and Mexico (+11.5%) combined for nearly 1.3 million sales for 18.6% of global vehicle sales.

The Asia/Pacific region saw vehicle deliveries rise 5.8% to 2.93 million units in the month, marking the largest volume since March, accounting for 42.8% of worldwide sales.

China, alone, took 23.8% of the global vehicle market in September, with 1.65 million deliveries, up 5.8% over year-ago.

Related document: World Vehicle Sales Summary

Japan finished the month in the No.3 position (behind China and the U.S.), with a sales drop of 2.1%, breaking an 11-month streak of double-digit declines.

Europe’s vehicle sales grew 3.2% to 1.85 million in September, garnering a 26.7% market share.

In the U.K., where registration laws skew sales-reporting toward the third month of each quarter, 376,000 new vehicles (up 0.2%) vaulted the nation to the No.4 sales spot worldwide.

The U.K. bump, along with strong sales in Brazil, pushed Germany (up 4.4%) and Russia (up 3.1%) out of top-five market positions held last month.

Vehicle deliveries in No.5 Brazil pushed up 1.7% in September over a strong year-ago, but growth in smaller markets including Argentina (+30%) and Chile (+24.9%) lifted South America sales 7.8%, giving the region 7.4% of worldwide sales.

Global vehicle sales in the year’s first nine months hit 58.2 million, a 5.1% improvement over year-ago.

Asia/Pacific (+0.5%) accounted for 41.3% of global vehicle deliveries in the period, down nearly two share points from like-2010. North America’s 19.9% share was up slightly from 19.1%, while Europe’s 26.3% share was nearly even with year-ago.