Toyota Corolla engine

Toyota, Honda, Mazda, Nissan, Subaru, Mitsubishi, Suzuki and Daihatsu have announced an alliance that will see a push to improve fuel economy from both gas-powered and diesel-powered engines by as much as 30 percent before the end of the decade.

The newly assembled Research Association of Automotive Internal Combustion Engines put the roughly $20-million project together, with the Japanese government committing to half the cost while the eight manufacturers will chip in the rest.

According to Automotive News, the automakers will team up and share basic research on internal-combustion engines in a bid to cut costs. Eventually, the results of the research will find its way into a production vehicle, although it's unclear just when we'll see the fruits of this partnership on the road.

While the manufacturers have aimed to make improvements by 2020, that goal is part of a larger, 10-year road map, which aims to improve the thermal efficiency of internal combustion engines to 50 percent. Currently, thermal efficiency in gas engines is at 39 percent while diesel is at 42.

The actual targets of improvements will be quite different based on the type of engine. Diesel mills, traditionally a weak point for Japanese manufacturers, will see a focus on reducing NOX emissions and particulate matter, while gas engines will aim for more complete combustion cycles while reducing knock.