Did U.S. auto sales hold strong in March?

We'll know for sure when official numbers are reported on Tuesday, April 2, but if analysts are correct, March was indeed another solid month for car and truck sales in the U.S.

Analysts polled by Bloomberg expect an average 4.2% year-over-year increase in U.S. sales of "light vehicles" (cars, pickups, and SUVs). At least one high-profile analyst, Edmunds' Jessica Caldwell, thinks March was likely the best month for U.S. light-vehicle sales since May of 2007.

While Ford (F -1.49%) will likely come in with an increase above the average, analysts say, the year-over-year growth winner looks set to be General Motors (GM 0.92%).

A good month as the General gathers strength
GM is expected to post a 12% year-over-year sales gain for March, according to the Bloomberg consensus analyst estimate. GM's full-sized pickups are likely to have been a big driver of any sales increase – Kelley Blue Book analyst Alec Gutierrez estimates that overall full-sized pickup sales were up 14.9% in March, and GM is known to be aggressively clearing out pickup inventories ahead of the arrival of redesigned models later this spring.

GM's increasing strength in cars is likely beginning to pay off as well. The Cadillac ATS and XTS sedans, both introduced last year, are set to benefit as GM's efforts to revive its old luxury brand gather steam. And GM has more new vehicles on the way: The company is introducing 13 new Chevrolets in 2013, as well as another Cadillac, the mid-sized CTS, due at dealers this fall.

Meanwhile, Ford will likely bask in a strong result for its midsized Fusion sedan, introduced late last year. Kelley Blue Book estimates that Fusion sales will be up 24% over year-ago totals for the last-generation model, itself a strong seller.

Tight supply and strong demand at Ford
Ford is probably selling all the Fusions it can make at the moment, as its factories are at full capacity – and in some cases, beyond. The company is adding 1,200 workers at its plant in Flat Rock, Mich., to build additional Fusions starting later this year.

Ford's production capacity challenges extend well beyond the hot new Fusion. While the impressive utilization of its factories has meant big profits in North America, the company is likely to be facing tight supplies for a few more months as it works to squeeze more production out of its existing North American factories.

That will likely keep the Blue Oval's sales increases relatively subdued, at least for a few more months, even as new models bring nice gains to GM. But Ford shareholders can take comfort: Those busy factories should continue to drive strong North American profits for the Blue Oval.