The humble family sedan was once inseparable from American culture, the prime mover of suburban commutes and summer road trips. But most Detroit automakers are ridding their lineups of sedans and diverting investment to S.U.V.s and crossovers, not to mention electric vehicles and self-driving tech.

Detroit’s Asian and European rivals see things differently. They’re continuing to invest in smaller cars, in part as a hedge against changing consumer tastes or soaring fuel prices. The outcome of these bets could help determine the competitive fates of automakers in America.

For Detroit companies especially, the PowerPoint is on the wall: For years, their car lineups have consistently lost money, with sport utility vehicles and pickups delivering virtually all their profits.

That situation was already bad in the recessionary depths of 2009, when cars outsold so-called light trucks — S.U.V.s, pickups and minivans — for the last time. Since then, Americans have gone even more crazy for S.U.V.s and pickups.