In Japan, the manufacturer Mazda solved the engine's chatter marks problem, by reducing apex seals' weight, that made it entering resonating vibrations. The engine has been successfully used by Mazda in several generations of their RX-series of coupés and sedans, including the Mazda Cosmo, R100, the RX-7 and more recently the RX-8. Mercedes-Benz completed its C111 experimental model in 1969 with 3-rotor Wankel engine. In 1970, the next model had a 4-rotor Wankel engine and could reach top speed 290 km/h but never reached serial production.