The SKY-G family of engines was just unveiled at the Tokyo Motor Show a couple months ago, but already word of one of the first applications is on the loose, and it looks like it'll be the 2011 MX-5. The report, though not official, says the sporty little Mazda could be good for as much as 70 mpg.

That's a tall figure, and expectations for the SKY-G in the MX-5 are thought to be closer to 50 mpg, but that's still a very efficient roadster. The SKY-G engine that's tipped for the application is a 1.3 or 1.5-liter version of the  four-cylinder, direct-injection high-efficiency engine.

The SKY-G engine shown in Tokyo was not given a power rating, but it was claimed that due to the improved engine block design both efficiency and torque are improved by about 15% over Mazda's current engine. Provided similar power bands and rev ranges, that could mean about 105 pound-feet of torque and 125 horsepower, adjusted for the SKY-G's smaller displacement. These numbers are purely speculative at this point, however.

While 70 mpg might seem like a very high target for an engine with such output, the next-gen MX-5 could be as light as 2,200 pounds, based on Mazda's previous statements on the next-gen car, and that it wants to move back toward the styling and proportions of the original 1989 car. Inspiration, though not likely structure, will be drawn from the MX-5 Superlight concept shown at the Frankfurt Motor Show.

We'll have to wait for an official announcement from Mazda, but the return of a low-power, lightweight but still eminently fun-to-drive roadster with the addition of 50+mpg efficiency is something just about any enthusiast can look forward to. Let's just hope they keep it large enough inside for the six-foot-plus crowd to get behind the wheel.