Chrysler Group, helped by another month of robust deliveries at the Chrysler, Jeep and Ram truck brands, posted a 30 percent increase in sales last month, while General Motors and Ford posted smaller gains compared to May 2011, when industry volume dropped on inventory shortages following the earthquake in Japan. Toyota Motor Corp. said its sales rose 87 percent from a year earlier, when Japanese automakers began to reel from that country\'s March 2011 earthquake. The company said more details would be released later Friday. GM said its sales rose 11 percent last month, with deliveries at Chevrolet up 10 percent, GMC demand up 19 percent and Buick volume rising 19 percent. Cadillac\'s slump continued with sales off 15 percent. GM\'s closely watched retail sales--roughly 70 percent of overall deliveries--rose 14 percent while fleet sales inched up 3 percent last month, the automaker said. At Ford, sales rose 13 percent, with deliveries at the Ford division advancing 13 percent and offsetting a 2 percent drop at Lincoln. Nissan Motor Co. said its May sales rose 21 percent to 91,794 units and Volkswagen AG said VW brand volume increased 28 percent. U.S. auto sales for last month are forecast to climb significantly compared with May 2011, when the annualized sales rate dropped to 11.7 million units, largely because of light vehicle shortages at Japanese automakers after the March 2011 earthquake and tsunami in Japan. Other automakers will release May sales results later Friday. Overall light-vehicle sales in May could climb 31 percent to 1.39 million units, based on the average estimate of nine analysts tracked by Bloomberg. And industry sales are expected to run at a 14.4 million seasonally adjusted annualized rate, based on the average of 14 estimates from analysts polled by Bloomberg. That sales pace would keep the U.S. auto industry on track for its best showing since 2007, when sales totaled 16.15 million. Chrysler on Friday estimated the annualized sales rate will total 14.2 million units in May. Chrysler brand sales surged 81 percent, while Jeep sales rose 24 percent and Ram truck demand jumped 23 percent, the automaker said. Fiat 500 deliveries jumped 128 percent to 4,003, and sales of the Chrysler 200 mid-sized sedan rose 87 percent to 13,250. It was the 26th consecutive month Chrysler\'s sales have advanced, and the 12th straight month the gain has been 20 percent or more. \"In spite of a tremendous amount of global economic uncertainty, the U.S. vehicle sales industry continues to power ahead,\" Reid Bigland, the head of Chrysler\'s U.S. sales operations, said in a statement. Chrysler\'s U.S. sales have increased 33 percent this year to 689,257 units. The automaker has been aided by a revamped large and mid-sized car lineup, a redesigned Jeep Grand Cherokee SUV, as well as fleet orders and some of the industry\'s highest retail discounts. Chrysler also offered a sales promotion late last month that delayed the start of payments for 90 days on certain models. \"The Japanese competitors are now back fully in the marketplace,\" Chrysler CEO Sergio Marchionne told reporters on May 24. \"It\'s something that we have not had to deal with, effectively, over the last 12 months.\" Industry sales started strongly early in May, softened during the middle of the month \"and then came back again over the Memorial weekend,\" Jonathan Browning, CEO of Volkswagen Group of America, said this week. Light vehicle demand--a bright spot in the U.S. economy--has climbed 10 percent this year through April and the annualized sales pace has topped 14 million units each month. \"Pent up demand continues to fuel auto sales at a steady and sustainable level,\" said Jesse Toprak, head of market intelligence at TrueCar.com. Easing credit conditions, fleet deliveries and a steady but sometimes choppy rebound in the U.S. economy are also driving industry sales. Analysts say automakers have also caught a break with the recent drop in gasoline prices nationwide. The rise in sales is prompting automakers to boost output by adding overtime and production shifts. Ford said today it will increase third-quarter production across North America by 5 percent to 690,000 units. Among the biggest automakers, GM, Ford and Honda have lost market share this year, while Chrysler, Toyota, Nissan and the Hyundai-Kia Group have gained ground. Some automakers were also forced to hike incentives to coax buyers into showrooms last month. Suzuki, after posting a 17 percent drop in April sales, introduced 0 percent financing on 72-month loans across its U.S. lineup. Ford said it raised incentives in May after falling short of sales targets in April, when its deliveries dropped 5 percent. \"Incentives are expected to play a larger role in May than in the past few months when pent-up demand drove consumers back to the market,\" Jeffries analyst Peter Nesvold said in a research report on Thursday. GM offered \"substantial\" increases in rebates for pickups and SUVs, while Ford boosted discounts on models such as the Fiesta and Focus cars, Escape SUV and F-series pickups, Nesvold said. Edmunds estimates automakers spent an average of $2,135 on incentives per vehicle in May, up 3.9 percent from April, and up 0.6 percent compared with May 2011. TrueCar.com said average incentive spending per new vehicle totaled $2,392 last month, an increase of 4 percent from May 2011 but a drop of 2 percent from April 2012.