The American consumer displayed an undiminished appetite for automobiles in May, so long as Ford (NYSE:F) didn't make them. Every other major manufacturer witnessed gains, boosted by a pronounced shift away from trucks and toward small cars and crossovers (an ambiguous category encompassing many car-based SUVs).

Toyota (NYSE:TM) is perhaps best positioned for this shift in consumer preferences. Prius sales, up 185% over last May, reached a record 24,000 units, and overall sales at the company advanced 14%. Perhaps more surprising was General Motors' (NYSE:GM) strong month, up 9.6%. GM is finding traction with the Impala (up over 50%), and its revamped Saturn line of cars and crossovers.

I could make a quip about Ford investors requiring shock absorbers, but the struggling company's results should really not surprise anyone. Ford's profitability -- kind of an oxymoron today -- is hitched to trucks and pickups like the F-Series, but that particular line is years old and losing steam (down 11.7%) relative to the GM's Silverado (up 15%) and Toyota's Tundra (up 122%).

Reports have noted that Toyota sold more units than Ford in May, knocking big F into the number three spot. That should be the least of Ford investors' concerns. If the company does actually manage to improve profitability, it will have to come at the expense of a smaller footprint.

One other trend worth noting is the significant discounting that is going on in the auto group. Toyota hiked its incentives by 29% to an average of $1,140, and Honda (NYSE:HMC), which boosted sales 1.8% in the month, notched a record average discount of $1,399 per vehicle. I wouldn't expect these companies to do anything too rash here, but it's certainly a data point worth following. Profit margins on cars are razor-thin, and just a fraction of those realized on SUVs, so deeper discounting is not a sustainable approach given the shift in demand toward compacts and subcompacts.

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Fool contributor Toby Shute doesn't own a car or shares in any company mentioned. The Motley Fool's disclosure policy can do 0-60 in 4.7 seconds.