General Motors Co. expects the popularity of its newest products to continue to spur sales over the coming months, while deliveries to fleet and commercial customers will decline to about 25% by year’s end from a robust 34% in the first five months.

According to Ward’s data, GM dealers sold 223,430 light vehicles in May, up 17.5% from 190,147 cars and trucks in 2009, when a flailing economy and the auto maker’s jump into bankruptcy weighed heavily on demand.

Tuesday marked the 1-year anniversary of the former General Motors Corp.’s historic Chapter 11 filing, which lasted 39 days and produced a new company shrunken to four brands from eight.

With both the economy and GM’s image on the mend, the auto maker says its remaining brands accounted for 222,305 sales in May, up 31.8% compared with year-ago.

Steve Carlisle, GM’s U.S. sales chief, says Chevrolet, Cadillac, Buick and GMC garnered 30,430 more deliveries in May than all eight brands did in like-2009. So far this year, the smaller GM has outsold its former entity by more than 100,000 units.

Against those numbers, Carlisle adds, the average transaction prices on GM vehicles are rising, as are residual values, while incentive spending is on the decline.

“The health of our brands is good and improving on a steady basis,” he tells journalists and Wall Street analysts during a conference call today.

“Our launch products continue to fuel these sales increases. And, most important, progress is not limited to just one of these brands, or one of these products; each of our brands has new vehicles that have been well-received by consumers.”

In fact, Carlisle says, launch products such as the Buick LaCrosse, Chevrolet Equinox and Cadillac SRX now account for one in every four cars sold by GM at retail.

Launch products also are winning GM new business. For example, 42% of LaCrosse buyers come from outside GM and 20% previously owned an import. “That’s pretty good,” Buick-GMC sales chief Brian Sweeney says of the LaCrosse.

The Chevy Camaro and Equinox are seeing conquest rates of 50%, the sales executives claim.

GM expects to lure more buyers away from competitors this summer when the new-for-’11 Chevy Cruze compact car launches – targeting shoppers traditionally owning Toyota and Honda brands.

But Alan Batey, who heads Chevrolet sales, says the auto maker does not intend to target owners of vehicles from rivals with specific programs.

“We believe our product right now is in a place where we have got to focus on ourselves, not other people,” he says. “We do not have expensive targeted actions against certain types of competitors.

“Frankly, we’ve got a lot of pull on our product right now, and that’s why we’re running our plays over an extended period of time and really starting to build the equity.”

GM also will see the Cadillac CTS Coupe, CTS-V Coupe and Chevy Volt extended-range electric vehicle launch later this year, while the Buick Regal sports sedan just left the gates last month.

“There’s plenty to look forward to, to build on our momentum,” Carlisle says.

Inventories of launch products, however, remain low and even with recent decisions to raise production at key assembly plants, the GM executives admit the lack of product continues to cost the auto maker sales.

Volume-brand Chevrolet finished May with a days’ supply of roughly 50, and stocks of the Equinox are about half that level. Typically auto makers like an average of 60 days’ supply for a given product.

“Those capacity increases are just starting to come along in the next month or so,” Carlisle says. “We have a plan in place, and we will start to see the benefit in the next 45 days or so.”

GM ended May with roughly 408,000 vehicles on dealer lots, or some 22,000 fewer units than April and down about 267,000 from like-2009.

The auto maker’s sales numbers also drew momentum in the month from deliveries to fleet and commercial customers, such as rental agencies and governmental organizations.

GM sold 83,305 cars and trucks to the fleet and commercial market, up 44% compared with year-ago and roughly 38% of its total sales. So far this year, deliveries are up 34% and represent 33% of the auto maker’s total mix.

Carlisle points to restocking at rental agencies, which held off on buying vehicles during last year’s recession and also are turning over their fleets to take advantage of higher used-car prices.

“There is some restocking there,” Carlisle says, predicting fleet and commercial deliveries will slip below 20% each month as the year rolls on and finally settle at a more traditional level of roughly 25% of sales.