BMW is updating the powertrain inside of its plug-in hybrid, an upgrade that will bring the i8's horsepower up to 450HP from 357HP, according to a report from Auto Express.

Claims of BMW's push to pump more horsepower out of the i8 emerged from sources inside the automaker's "i" division, according to the report. The new i8 could launch next year.

BMW engineers want to make better use of the i8's lightweight, carbon fiber build, the sources stated, so the engineers are improving the car's gas engine—the i8's electric drive will remain unchanged.

To keep up the i8's pep, the newer version of the car could get rid of its rear seats and make use of unpainted carbon fiber panels to offset the added weight of the larger four-cylinder engine, the report claimed. The engineers are targeting acceleration of zero to 62 in 4.4 seconds.

The new i8 is expected to separate itself from its predecessor visually as well, a move that could help BMW heat up competition on the market for hybrids and drum up more sales of the popular plug-in by simply offering prospective i8 customers another option for a bit more money.

BMW has sold more than 10,000 i series vehicles this year and is coming off a strong performance in May. Last month, sales of the BMW Group's BMW brand were up by about 4 percent and up by about 5.2 percent so far this year.

BMW Group delivered 159,129 BMW vehicles to customers in May and 759,609 automobiles since the start of 2015.

"The solid growth the BMW Group has achieved this year continued in May, with all sales regions recording an increase in sales," said BMW Board of Management Member Ian Robertson. "Our innovative, new products are achieving pleasing sales around the world and I am delighted that we have sold over 10,000 BMW i vehicles in the first five months of this year."