Complex sentence: Like its predecessors, the Morris Oxford for the 1960s was a four-cylinder family car which would have been seen as mid-sized in the UK, which is where most of the cars were sold.
Split into simpler sentences: Like its predecessors, the Morris Oxford for the 1960s was a four-cylinder family car. It would have been seen as mid-sized in the UK, which is where most of the cars were sold.