General Motors Co and Nissan Motor Co sales surged in February as incentives drove shoppers to dealerships and outweighed concerns about higher oil prices.
GM sales were up 46 percent, more than double the expected growth for the industry as a whole. Sales for Nissan jumped 32 percent.
Ford Motor Co and Chrysler Group lagged, with sales gains of 14 and 13 percent, respectively.
The boom for GM and Nissan came on the back of stepped-up incentives for car buyers and dealers in a traditionally slow month for vehicle purchases and at a time when rising oil prices have emerged as a new threat to the industry.
The success of the aggressive discounts by both GM and Nissan in February raises the prospect that rivals will respond with stepped-up incentives of their own, cutting into projected profits across the industry, analysts have said.
Shares of Ford and GM were both down almost 2 percent in early afternoon trading.
The recent rise in oil prices could slow or even derail the industry's recovery in sales, now in its second year, analysts and industry executives have said, although little of that feared impact was visible in the February sales results.
U.S. gasoline prices rose to $3.38 a gallon in the past week, the biggest jump since 2005 when Hurricane Katrina disrupted petroleum supplies, the U.S. Energy Department said.
But trucks remained popular in February with American buyers. Sales for Nissan's Pathfinder SUV and GM's Chevrolet Silverado pickup truck both rose 60 percent.
Both GM and Nissan said they had already throttled back their spending on the sales incentives that had allowed both to improve market share in February.
Our goal is very clearly to continue to have a very disciplined approach, GM sales chief Don Johnson said. Our incentive costs will start to moderate in March.
GM: NO REPEAT OF PAST MISTAKES
During its long slide into bankruptcy in 2009, GM had relied on heavy discounting to drive sales at the expense of profits.
But Johnson and other GM executives said that the automaker would remained disciplined on pricing with inventories down to a relatively tight 60 days supply of sales at dealerships.
Nissan, where dealer stock was equal to 68 days' supply of sales at the end of February, also said it had reduced its spending on incentives this month.
It's competitive out there on incentives, said Nissan's U.S. sales chief, Al Castignetti. But you have to ask yourself how much you can really juice it when you're not carrying the kind of inventory that you used to.
Hyundai Motor Co, which has been winning market share with its line-up of lower-cost vehicles, said the incentives on offer in February had already tipped the low-margin industry into a price war.
Said GM's Johnson: We're not surprised that some of our competitors have started talking about our performance as a way of explaining their performance.
In a measure of its momentum in February, GM's Cadillac CTS sedan outsold the six combined models under Ford's luxury Lincoln brand.
The sales results represent one of the first snapshots of U.S. consumer demand, and the February data was expected to show steady demand without evidence of the kind of accelerating turnaround that some analysts had forecast.
Pump prices averaged $2.79 for all of 2010 when U.S. vehicle sales began to recover, according to industry data.
Customers in the U.S. are the most sensitive to oil prices. When they go up, hybrids fly out of showrooms and SUVs and pickup truck sales fall, Toyota Executive Vice President Takeshi Uchiyamada told reporters on the sidelines of the Geneva auto show.
The effects could spill over to Europe too, Ford's chief financial officer, Lewis Booth, warned.
If prices remained high for long enough they may affect the economic recovery of Europe, he said on Monday.
For the fifth consecutive month, the annualized sales rate is expected to hold above 12 million vehicles in February.
The average forecast of 41 economists surveyed by Reuters was 12.6 million vehicles on that basis for February, about flat from the sales rate in December and January.
GM's Johnson said early sales data for February pointed to a sales total near 13 million units on an annualized basis.
(Additional reporting by Helen Massy-Beresford, Bernie Woodall and Chang-Ran Kim in Geneva, editing by Matthew Lewis)