Some of the new mildly turbo'd vehicles can take regular unleaded but you will get diminished performance and mileage. The numbers they give you are from E93. I wouldn't suggest running a turbo'd vehicle with E89 for long, same goes for a "premium" or "performance" engine. If they suggest E93 it's usually for a reason (they run hotter) and if you run anything lower you will start to get knocking (which the car will compensate for) and again, reduced performance and mileage. Our car does not require it but I thought about getting some of the Shell V-Power (E93) last week because prices were so freegin cheap here and because it has more detergents to clean the engine. Figured 1 half tank fill may do it some good but decided against it. Shouldn't hurt it but I would probably be running rich.