(ANSA) - BELGRADE, DEC 1 - "After 2035, in addition to purely battery-electric vehicles, cars with dual propulsion systems consisting of a battery and combustion engine should continue to be registered, provided that residual emissions from the automotive and fuel sectors are offset," wrote the German Federal Chancellor in a letter to European Commission President Ursula von der Leyen. In addition, the letter emphasises the importance of focussing on highly efficient combustion engines. (ANSA).