Small SUVs are providing a window for zippy turbo-threes, while V-8 and V-6 penetration slides as better four-cylinders arrive.

Three-cylinder automotive engines aren't about to dominate the US market. But over the past few years, the peppy powertrain has steadily nibbled share from other engine types.

Every quarter since 1Q 2019 has seen an increase in three-cylinder penetration into the US powertrain portfolio, according to S&P Global Mobility personal registration data. At the end of 2Q 2023, the rate had climbed to 5.6%; for the partial third quarter, it has hit 6.2%.

For perspective, the three-cylinder share was essentially zero as recently as 2019, said Tom Libby, associate director for loyalty solutions and industry analysis at S&P Global Mobility.

Source: S&P Global Mobility retail registration data

*Q3 2023 includes July only ©2023 S&P Global Mobility

Notably, the shift hasn't cut into the share of the market-leading four-cylinder powertrain, which has maintained more than half the market, with the share increasing to 57.2 percent in the past year.

Since 2022, six-cylinder engines have dropped from 28.6 percent to 26.8 percent share. And eight-cylinder engines have dipped from 11.5 percent to 10.9 percent. (Note: Shares by engine size - number of cylinders - refers to all possible engine sizes for light-duty vehicles, but niche engines like V-10 and V-12 are not displayed.)

The numbers might suggest that three-cylinders are gaining at the expense of six- and eight-cylinder engines. But Libby says it's not that simple. Three-cylinder engines have risen with the rising popularity of subcompact-plus utility vehicles such as the Buick Encore GX, Ford Bronco Sport, and Chevrolet Trailblazer.

Consumers are moving to those models to get a slightly bigger vehicle than subcompact utilities like the Chevrolet Trax or the original Encore, Libby says. The subcompact-plus utility segment "appears to have hit a sweet spot in terms of space," he says.

S&P Global Mobility data shows US new personal registrations of 589,026 for subcompact-plus utility models through July, compared to just 123,033 personal registrations for subcompact utilities.

Consumers moving up from a subcompact utility face a modest bump in monthly payments, from an average of about $422 for a subcompact, with a $40 increase to get into a subcompact-plus, according to AutoCreditInsight data supplied to S&P Global Mobility by TransUnion. Moving up further to a compact utility would entail about $ 100 per month in incremental payment from a subcompact-plus.

However, pandemic-related inventory shortages have made small-vehicle sales over the past three years "very unusual," Libby cautions. "Frankly, it's impossible to tell what normal consumer behavior is because of the inventories."

The dip in eight-cylinder powertrains, meanwhile, comes mainly from advances in six-cylinder engines, according to Libby: "In general, the manufacturers are making sixes that have just as much power as an eight, and much better fuel economy."

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This article was published by S&P Global Mobility and not by S&P Global Ratings, which is a separately managed division of S&P Global.