The gap between Mercedes and Ferrari was much smaller than the gap between Mercedes and Renault. This is also valid for reliability. Since we entered the hybrid area power units have not really been a strong point of Renault. These are not naturally aspirated v10’s or v8’s anymore.. these are hybrid engines with turbos... totally different cup of tea.Following that logic, it was impossible for Ferrari to build a better engine than Mercedes. And yet they obviously did this year. Power units have always been Renault's strong point. It is just a matter of time and allocating the right resources (and they have plenty in this area).