DON'T let the subtle, station wagon appearance fool you: underneath the RS4's skin lurks a mightily impressive mechanical package. The engine is the standout. Twin turbos, 280kW, words such as these roll off the tongue. But 173kW per tonne? That is one power-to-weight ratio to remember. For steering directness, roadholding and stopping ability it doesn't come much better than this - certainly not in family wagon form, which adds another interesting, practical and alluring twist to the RS4 story.