The company is promising a 20 percent improvement in fuel efficiency and claiming that the new Crosstrek Hybrid can drive more than 621 miles on a single tank of fuel.

Subscribe to TheStreet's free daily newsletter Toyota brought a pair of four-cylinder engines, Mazda showed off a revamped and reworked version of its signature Wankel rotary engine, while Subaru showed off a hybrid version of its signature flat "boxer" engine installed in a prototype version of its popular Crosstrek crossover SUV.

Subaru Corporation is set to unveil its highly anticipated next-generation hybrid technology in Japan. The initial launch will feature two new models, the Crosstrek and Forester, before U.S. customers get them.

Subaru's vehicles are beloved by their fans for plenty of reasons, but generally speaking, fuel economy isn't one of them. As a result, there's been plenty of interest in the automaker's vague plans to roll out hybrid models using a Toyota-based system in the near future.

With weak sales of its milquetoast Solterra and strong rivals in the hybrid SUV game like the Toyota RAV4 Hybrid and Honda CR-V Hybrid, it’s perhaps no surprise that Subaru’s next-gen hybrid powertrain system is shaping up to improve its stats in all areas.

Now, extended details have been published ahead of December when the Crosstrek will be the first model to utilize the next-generation hybrid system. At the heart of the new hybrid system is a naturally aspirated,