The push is on to keep up with the unexpedectly high demand for plug-in hybrid vehicles (PHEV) at Volvo.

Despite claiming that it would add electrification to every model in its lineup, Volvo says it has underestimated the demand for PHEVs and will increase production.

"By the end of the year we should be up to 20 to 25 percent," Volvo CEO Hakan Samuelsson told Automotive News. "We are not happy because we could sell more [plug-in hybrids]. We underestimated the demand."

Currently, Volvo's electrified models account 10-15% of sales in the models where it's available (everything except for the XC40, though that's set to change). But sales have been limited by Volvo's inability to produce enough batteries (and other key components), according to Samuelsson.

To correct this production bottleneck, Volvo will increase capacity beyond what it predicts sales will be at by the end of the year.

"We are tripling the capacity from what we had about a year ago to where we will be at the end of this year," said Samulesson.