The ZF eight-speed automatic transmission, available in diesel XFs, has helped achieve significant reductions in CO2 emissions. The 2.2 Litre AJ-i4D engine, featuring Intelligent Stop/Start technology, emits just 149g/km. Meanwhile, an aluminium differential casing, with low resistance bearings, along with the new transmission has cut CO2 readings for XFs powered by the 3.0 Litre V6 Diesel engines by 6% to 169g/km.