BMW Z4 E85 (2002 - 2008) - timing belt or chain?

Petrol engines

Model Power \| Displacement \| Cylinder \| Engine	Camshaft drive system Timing belt or chain
BMW Z4 2.0i 110 kW / 148 hp / 150 PS \| 1995 cc \| 4 \|N46B20	timing chain
BMW Z4 2.2i 125 kW / 168 hp / 170 PS \| 2171 cc \| 6 \| M54B22	timing chain
BMW Z4 2.5i 130 kW / 174 hp / 177 PS \| 2497 cc \| 6 \|N52B25	timing chain
BMW Z4 2.5i 141 kW / 189 hp / 192 PS \| 2494 cc \| 6 \| M54B25	timing chain
BMW Z4 2.5si 160 kW / 215 hp / 218 PS \| 2497 cc \| 6 \| N52B25	timing chain
BMW Z4 3.0i 170 kW / 228 hp / 231 PS \| 2979 cc \| 6 \| M54B30	timing chain
BMW Z4 3.0si 195 kW / 261 hp / 265 PS \| 2996 cc \| 6 \| N52B30	timing chain
BMW Z4 Alpina S 221 kW / 296 hp / 300 PS \| 3246 cc \| 6 \| E5/2	timing chain
BMW Z4 M 252 kW / 338 hp / 343 PS \| 3346 cc \| 6 \| S54B32	timing chain