Mercedes and Renault will unveil plans for a future collaboration at the upcoming Frankfurt Motor Show. This plans include to expand the Smart line-up by middle of the next decade, including a radical three-seater sports car, but also the revival of the four-seat Smart ForFour.

The last generation Smart ForFour was based on the Mitsubishi Colt and produced at Mitsubishi's NedCar plant in Born, Netherlands. But the next one will be a premium subcompact "different than others" and most probably offered as a plug-in electric version.

The Mercedes-Renault collaboration includes plans to build small-capacity gasoline and diesel units, including possibly a new generation of highly efficient three-cylinder engines already under development at Mercedes-Benz.

.