I hate to put a damper on things but i think this thread may lead some people astray.
1) Any fuel you blend yourself is not permitted for use under MSNZ regulations. This is to ensure that the fuel is consistent and meets the specifications set out by MSNZ, view the Fuel Chart at
http://motorsport.org.nz/Pdf/LiveMM34%20Book1%20App2%20SchA2.pdf. Manual 34 Book one schedule one article 3.9 states that E85 must be commercially available fuel purchased in NZ.
2) One of the main reasons for the introduction of E85 is to phase out leaded fuels. Blending ethanol with leaded fuels is definitely not a good idea. Putting aside possible chemical compatibility issues, regulations allow for a maximum of 5mg/l of lead in E85, leaded fuels usually contain up to 850mg/l of lead. Even 5% of a leaded fuel will put you more than 8 times over the allowed amount.
3) Additives are very important. pHe stabilisers control the acid strength of the fuel and therefore the corrosive properties, without this the ethanol can corrode aluminium parts in your engine and fuel system. Lubricity additives protect your fuel system from excessive wear, pumps, injectors and regulators will wear much faster without lubricity additives.
While it may seem that ethanol blended fuels are simply A + B = E85 there is a lot more to it. There are many different grades of ethanol and many different grades of petrol. All petrol at the pump contains additives, some additives are not good to blend together and some blend better with ethanol than others.
It is completely up to the individual what they want to put in their car but it is becoming apparent that MSNZ will harshly enforce fuel use in the upcoming season. Ensure you make an informed decision with your fuel and that you are aware of the consequences of using fuels that do not meet the regs.