Having signed a joint-venture agreement with Alfa Romeo back in January, details regarding Mazda's next-generation MX-5 and Alfa Spider are coming to light. While we know both cars will share a rear-wheel-drive platform and will be built at Mazda's Hiroshima plant in Japan, Auto Car is reporting the cars will also be powered by bespoke engines, with a diesel unit being considered for the MX-5. Due next year, Mazda's new sports car will feature a new naturally-aspirated SkyActiv gas engine with a capacity in the region of 1.6-liters and an output of 130 hp for the entry-level model.

Other units under consideration include a larger SkyActiv engine (turbochargers are unlikely to feature as Mazda doesn't want the MX-5 anywhere near forced induction) and a diesel engine. The Japanese carmaker is unsure how responsive the market will be to a small diesel roadster, while the lightweight, high-revving nature of a gasoline unit makes an oil-burner even less likely. Alfa Romeo will almost certainly use its 1.4-liter turbocharged "TB" engine in an entry-level Spider. Other powerplant possibilities include the more powerful MultiAir and the 4C's 1750 TBi units, with output ranging from 120 to 296 horsepower.

Both cars will come with six-speed manual transmissions, and weight-reducing measures should keep the MX-5 under 2,000 lbs. The Alfa Spider will boast typical Italian styling to further distinguish it from its Mazda cousin; something resembling the Pininfarina-penned 2uettottanta Concept (pictured) that debuted at the 2010 Geneva Motor Show would be most welcome.