In case you had any doubt, Toyota's (NYSE: TM) back: The Japanese giant's U.S. sales were up a whopping 87% in May over tsunami-ravaged year-ago totals, as the company left little doubt that it was back up to speed after months of natural-disaster-related challenges.

Toyota is on a global roll, making a strong bid to reclaim its former title as the world's largest-selling automaker. But the current title holder, General Motors (NYSE: GM), might have something to say about that.

A much-needed good month for Toyota
The year-over-year increases are eye-popping because of the huge production problems Toyota was facing last May in the wake of the March 2011 tsunami that devastated northern Japan (and many of Toyota's key suppliers). But the overall sales numbers are strong: Toyota's on a roll right now, and it should gain significant ground on its big rivals here in the U.S. as the year goes on.

High points? There were several:

  • Camry continues to be very strong. The all-new Camry sedan was released late last year to so-so reviews, but consumers seem to like it just fine: Sales of almost 40,000 units in May easily trounced totals posted by the rival Chevy Malibu and Ford Fusion and represented a 94% year-over-year increase.
  • Prius continues to rock the world. Now that "Prius" is a nameplate that covers three distinct hybrid models, the aggregated sales totals look huge -- but the lineup has in fact been posting big gains for Toyota. Total Prius sales were up 186% over year-ago numbers -- in part a reflection that Prius production was hit especially hard by the tsunami -- and the model is now the world's third-largest selling nameplate behind the Corolla and Ford (NYSE: F) Focus, a big achievement for a model that was once considered a niche product at best.
  • Bigger vehicles helped, too. While Toyota's pickup sales are just a fraction of what its Detroit rivals post every month, its small SUV, the RAV4, has been a strong seller for a long time. RAV4 sales were up 106% over year-ago totals in May, and the company's Sienna minivan also posted a nice gain.

Toyota still has work to do, but clearly its bread-and-butter products are doing well. The Camry, the Prius, and the Corolla -- which outsold Ford's strong-selling Focus in May -- are all finding lots of happy new owners every month, and that should drive more strong gains for Toyota as the year goes on.

But the competition isn't exactly going away.

General Motors isn't going away
GM's May sales were up 11% over so-so year-ago numbers, giving the still-recovering General its highest monthly total since the Cash-for-Clunkers-fueled surge in August 2009. That's a decent result, but the better news was that the proportion of (more profitable) retail sales versus (less profitable) fleet sales was moving in GM's favor: GM's retail sales were up 14% over last May's numbers.

Like ancient nemesis Ford, GM had success at both ends of the product spectrum during May:

  • Strong truck sales. Sales of GM's full-size pickups -- the Chevrolet Silverado and GMC Sierra -- were up 23% year over year. That's comparable to the increase seen at Ford, and it's further evidence that businesses and consumers are willing to spend to replace an aging pickup-truck fleet. GM's mid-sized pickups posted a 34% gain over year-ago totals, a solid increase in a market niche that Ford recently abandoned as it ended U.S. production of its Ranger model.
  • Big gains for big SUVs. GM's full-sized, truck-based SUVs like the Chevy Tahoe and Suburban have long been a bread-and-butter product for the General -- but high gas prices and the age of the current models (they're set to be replaced early next year) seemed to suggest that sales would slow. Not so: Sales were up 14%, with the Tahoe posting a gain of nearly 22%. Good news for shareholders, as these models are significant contributors to GM's bottom line.
  • Nice gains for smaller cars, too. It used to be that GM was dependent on its big trucks and SUVs, but not anymore: Nowadays, the General has strong entries at the opposite end of the product spectrum as well. Sales of GM's compact and small cars were up 16% over last May's totals, with the new Chevy Sonic subcompact continuing to outsell its crosstown rival, the Ford Fiesta. Sales of the Chevy Cruze compact have slowed somewhat, though -- the Cruze made big gains a year ago, as supplies of the Toyota Corolla and Honda (NYSE: HMC) Civic dried up, but it was down almost 14% over those strong year-ago numbers, even as Ford's Focus made gains.

Not all the news was good -- among other concerns, Cadillac sales were down, with the brand awaiting several key new products. That's a familiar theme: I've said before that GM is still treading water to some extent, as its global product overhaul continues to gather steam. GM vice president Don Johnson said Friday that about 70% of GM's models would be "new or freshened over the course of 2012 and 2013" as the General's long-awaited product renewal efforts bear fruit.

That's a good thing. With Toyota surging and Ford continuing to hold its ground, new products might be just what GM needs to reward its patient shareholders. While GM's stock could have significant upside in coming months, we've run across another stock pick that has so much promise that we've dubbed it "The Motley Fool's Top Stock for 2012." This company is revolutionizing commerce in Latin America and could be a golden opportunity for savvy investors. You can get instant access to the name of this company and the full story -- download it now.