General Motors Co GM.UL posted a 6.4 percent increase in U.S. auto sales for April from a year earlier, lagging an expected rise of about 20 percent in the overall industry which has been helped by incentives.

Excluding GM's discontinued brands, the automaker reported a 20 percent increase in its Chevrolet, Cadillac, Buick and GMC brands in April from a year earlier when a recession-beaten auto industry was bracing for bankruptcies by GM and Chrysler.

Chrysler filed for bankruptcy at the end of April 2009 and is now under management control of Italy's Fiat SpA. GM followed with a government-funded bankruptcy a month later.

On a sequential month basis, U.S. auto sales are expected to be down slightly from March with automakers trimming incentives as a whole, but with year-over-year sharp increases in incentives from Toyota Motor Corp.

Toyota is expected to post a second consecutive month of sharp year-over-year gains due to uncharacteristically high incentives aimed at jumpstarting U.S. sales that tumbled in January and February amid massive safety recalls.

Edmunds said on Monday Toyota's incentives were up more than 50 percent in April from a year earlier to $2,498 per vehicle, but were below the industry average of $2,654. They were down 9 percent from March.

Among the biggest automakers, Ford Motor Co (F.N), Hyundai Motor Co (005380.KS) and Nissan Motor Co Ltd (7201.T) also are expected to post sales increases that exceed the expected 20 percent increase in the industry overall.

Hyundai, Ford and GM had sales momentum that allowed them to cut back on incentives and let their products sell themselves, senior analyst Michelle Krebs said in a statement.

Chrysler sales also may be at or slightly above the industry increase overall for April from a year earlier.

The U.S. results follow a sharp jump in April sales in Spain that was supported by government incentives to scrap older vehicles, and a slight 1.9 percent car sales increase in France where such incentives were pared.

Automakers are still counting on a broad U.S. economic recovery to lift sales rather than costly incentives that hurt profit margins and used car prices.

Overall, the U.S. economic recovery would appear to be on track, however the pace isn't expected to be as robust as compared to other post-war recoveries -- kind of a slow and steady sort of scenario, GM Vice President of U.S. sales Steve Carlisle said on a conference call.

Sales to government, corporate and car rental groups also are expected to be up in April from depressed levels in April 2009.

GM said that its incentives were down slightly from March and down $1,100 from April 2009.

In the seasonally adjusted annualized rate economists track, U.S. auto sales in April are expected to come in at about 11.4 million vehicles, up sharply from 9.3 million a year earlier, but down from 11.8 million in March.

GM said the industry annualized sales rate likely tallied about 11.1 million light vehicles for April.

The industry in 2010 is expected to snap a four-year drop in U.S. auto sales that reached 10.4 million vehicles in 2009, the lowest total since the early 1980s even without adjusting for population increases.

U.S. auto sales were nearly 17 million vehicles in 2005 and industry experts believe a rebound to the 16 million vehicle range last reached in 2007 could take several years.

(Reporting by David Bailey, Soyoung Kim and Bernie Woodall, editing by Matthew Lewis)