Brace yourselves, this ride is only going to get bumpier.

Automakers’ sales in the U.S. struggled for yet another month, data Tuesday showed. Gas-guzzlers continued to gain market share and, for the first time in history, the market share of sedans dipped below 30 percent. On the back of President Trump’s trade rhetoric, imports dropped too.

The pain was even greater for Japan’s Toyota Motor Corp., Nissan Motor Co. and Honda Motor Co. Toyota’s Camry posted a 19 percent sales drop last month while Honda’s Accord registered an 11 percent decline. The trio’s Tokyo-traded stocks fell, bringing Honda’s retreat this year to more than 17 percent. Toyota and Nissan are down more than 6 percent.

Investors should have expected this. U.S. economic data may have been heartening, but the reality of the car market hasn’t changed. Profitability remains tough and demand has shifted to light trucks from sedans and other models. As Cox Automotive’s senior economist Charlie Chesbrough put it, “the economy may be peaking right now, but the vehicle market likely peaked two years ago.”

The Japanese automakers mostly manufacture sedans, and as sales slide they’re no longer willing to expand incentives in an attempt to reverse the trend. That’s understandable. Even if American  consumers do become willing to spend more on vehicles, their tastes won’t just change – especially when offerings from U.S. car companies are leading them in the opposite direction. 

SUVs and trucks are high-margin products, so carmakers are pushing them hard. Having lost ground in China, Ford Motor Co., Fiat Chrysler Automobiles NV and General Motors Co. are doubling down in the U.S. Ford now looks more like a truckmaker than a carmaker: The F-series truck line had a blockbuster August, while its sedan sales slumped 30 percent. Ford’s Explorer and Expedition SUV models also gained sharply.

Even the boom in SUV sales portends potential trouble. Rising demand has been driven by consumer incentives and discounts, a sign of automakers’ desperation. The risk is that incentives will eat too much into profitability, causing carmakers to pull back and sales to start falling. This has been a familiar syndrome for the wider U.S. car market in the past two years:  particularly at Nissan, as we have written.

For now, it’s not happening. As Ford executives noted in a call Tuesday, SUV incentive spending rose for the industry, but was down for cars and vans.

Yet there’s more evidence the trend isn’t headed in the right direction. Average transaction prices rose across the industry by around 2 percent in August from a year earlier, with Toyota’s climbing 2.3 percent and Honda’s 4.2 percent, according to Cox Automotive. But SUV prices were flat, especially for smaller models. As competition piles up, incentives will only increase in this segment.

Eventually, SUV makers will feel the pain, too.