New vehicle sales froze through early March due to harsh winter weather, but automotive sales are thawing in spring and beginning to grow. Let's take a look at the results from Detroit's Big Three automakers and see what to expect in the months ahead. 

GM's Chevy Silverado sales moved higher in April. Source: General Motors

General Motors: 254,076 (7% increase)
General Motors (GM 0.40%) has battled through massive amounts of negative publicity, and deservedly so, surrounding its massive recall debacle during the first four months of the year. Despite recalling nearly 7 million vehicles, which caused the automaker to barely remain profitable in the first quarter, it hasn't had much of an effect on the company's sales yet. 

General Motors' Chevrolet brand led the charge in terms of sales volume with a 5.3% increase to 181,648 sales in April. GMC posted the largest year-over-year gain with a 13% increase to nearly 40,000 vehicles delivered in April. Buick and Cadillac brought up the rear, in terms of volume, with 12% and 5.1% increases to roughly 19,000 and 14,000 units delivered, respectively.

General Motors stock price was trading roughly 2% higher at the time of this writing; perhaps because investors expected a dip in sales resulting from the negative recall publicity and were pleasantly surprised with the 7% gain. Also, another very positive sign for investors was that General Motors' two full-size trucks -- also the automaker's most profitable products -- posted gains. The Silverado and Sierra posted 8.5% and 21% increases after sales spiraled downward significantly for the first two months of 2014.

Moving on to highlights from America's second-largest automaker, Ford Motor Company (F 0.30%), it was a slightly disappointing month.

Ford's Explorer posted a great sales month. Source: Ford Motor Company

Ford: 211,126 (1% decrease)
Ford's sales in April were down just slightly compared to last year, although it can partially be explained by significantly lower rental sales. Ford considers "high-quality" sales -- those that are more profitable -- as retail, commercial, and government; those sales checked in 1% lower, and 16% and 21% higher, respectively. Ford's overall sales decline was partially explained by a decline in rental sales, which dropped 24% in April. 

Ford has expected rental sales to decline as management continues to focus on improving the profitability of its sales mix. That said, investors would like to see retail sales move higher in the months ahead.

There were some bright spots in Ford's slightly disappointing April. Ford's F-Series sales topped 63,000 units in April which was a 7.4% increase over last year. The F-Series continues to sell well despite being the oldest design among competing full-size trucks. Furthermore, the average transaction price of F-Series trucks has climbed $1,200 over last year to an average of $39,000 -- a huge win considering older designs typically fall in transaction prices ahead of a new model launch.

Ford considers any month the F-Series breaks 50,000 in sales a solid month, and this will help power company profits while the launch of the redesigned F-150 hits dealerships soon.

Another bright spot in Ford's figures was the Explorer, which posted its best April sales performance since 2005 with over 16,600 units sold. That's a 17% increase and crowns the Explorer America's best-selling midsize utility, according to Ford.

Fiat Chrysler: 156,698 (14% increase)
While Chrysler trails both Ford and General Motors in terms of sales volumes, it continues to increase sales at a faster pace and climbed 14% last month, its best April since 2007. The big results were driven by the company's Jeep brand, which posted a sales increase of 52% in April, which marks the Jeep brand's best sales month in history. 

Another bright spot for the freshly merged Fiat Chrysler Company was the 17% sales increase for its Ram Truck. That was the trucks best April sales performance in history and helped drive the overall Ram brand to a 22% monthly increase, compared to last year.

"Strong consumer demand for our Jeep sport-utility vehicles and Ram pickup trucks continued in April as Chrysler Group extended its streak to 49-consecutive months of year-over-year sales gains," said Reid Bigland, head of U.S. sales, in a press release. "The spring selling season is heating up as our Jeep brand had its best monthly sales ever."

Looking ahead
April continued to calm anxiety about the automotive industry's slow start to 2014 and sales look to continue higher as interest rates remain low, many new models are scheduled to launch, and the housing and labor markets gradually improve. 

What investors should watch as we continue through the year is if Ford's sales can rebound, as its car sales continue to drag monthly results lower, amid the company's most aggressive launch of new products. Those launches will be costly to the company in 2014 but should set Ford up for major sales improvements in the years ahead.

Investors must also watch if General Motors' sales reverse and head lower while its massive recall saga continues. Expect Fiat Chrysler to keep posting significant increases due to its easier year-over-year comparisons and its increasing sales from the company's recently refreshed Jeep products and thriving Ram truck brand.