While other automakers are moving away from plug-in hybrids to electric powertrains, Volvo is finding unexpected success with its lineup of plug-in hybrids.

At a recent roundtable with journalists in Sweden, Volvo CEO Hakan Samuelsson said the company is disappointed that it underestimated demand for its plug-in hybrids.

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"We are not happy because we could sell more [plug-in hybrids]," he said, according to Automotive News (subscription required.) "We underestimated the demand." He said the company did not have a big enough supply of batteries, motors, and other electrical components to build more of its plug-in hybrids, which sell for about 30 percent more than non-hybrid versions of the cars.

Samuelsson said the company will boost its capacity for those plug-in hybrid components for 2019, from its current 10 or 15 percent worldwide, up to 25 percent of its sales.

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Last year in the U.S., Volvo sold a little less than 1,500 XC90 T8 PHEVs, a little more than 2,100 XC60 T8 PHEVs, and fewer than 500 S90 T8 sedans, but it sold almost 27,000 plug-in hybrids in Europe, combined.

At the same time, the company announced an upgrade to upcoming XC60 and XC90 T8 hybrids to boost their plug-in range by about 15 percent.

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The new models haven't been rated by the EPA, but current models have an estimated 17 miles of electric range, which would put the new ones up around 20 miles. The Volvos use a 2.0-liter turbo-4 and an 8-speed automatic transmission to drive the front wheels, and an electric motor to provide another 87 horsepower and 177 pound-feet of torque to the rear wheels.

Volvo also announced a new B5 line of mild-hybrid SUVs for Europe.

Other automakers, such as Audi, BMW, and Jeep have also announced plans to boost their lineups of plug-in hybrid SUVs, earlier this month at the Geneva auto show, so the new Volvos will have plenty of competition.