[Clan]

The reason i ask is that firstly the car will use 40% more E85 fuel than petrol which for a start makes it completely uneconomic as it is only slightly cheaper than petrol ..

If the engine is made specificly to run only on E85 by having a very high compressions ratio ( Like a GDI ) it will be more efficient .. but these dont exist yet .
The volvo flexi fuel will run on any combination of E85 and petrol .

The volvo Flexi-fuel has many modifications :
The fuel is corrosive so stainless steel pipes are used and special injectors which also have a much greater fuel flow to cope with the greater volumes of fuel being injected .
Different gasket materials are used where in contact with the fuel .
E85 is electricaly conductive which means a special fuel pump in the tank is needed .
The engine managment can detect the mix of petrol and E85 and adapt to suit ..
The contact between the fuel and any alluminuim and rubber must be eliminated .

so thats why i asked what advantage is there in using it apart from the emissions being much less but at a higher cost to you ...