Complex sentence: The most powerful American BMW E30 in 1989 came in the form of the M3, using a 192 hp (143 kW) "S14" straight-four with a four-valve head adapted from the "M88" six and Bosch fuel injection.
Split into simpler sentences: The most powerful American BMW E30 in 1989 came in the form of the M3. It used a 192 hp (143 kW) "S14" straight-four with a four-valve head adapted from the "M88" six and Bosch fuel injection.